Chapter 17: Physical and Cognitive Development in Late Adulthood

Hearing in late adulthood

"Mom, I'd like you to meet Joe's cousin Leona," said Ruth's daughter Sybil at a Thanksgiving gathering. But in the clamor of boisterous children, television sounds, and nearby conversations, 85-year-old Ruth didn't catch Leona's name or her relationship to Sybil's husband, Joe. "Tell me your name again?" Ruth asked, adding, "Let's go into the other room, where it's quieter, so we can speak a bit." Reduced blood supply and natural cell death in the inner ear and auditory cortex, discussed in Chapter 15, along with stiffening of membranes (such as the eardrum), cause hearing to decline in late adulthood. Decrements are greatest at high frequencies, although detection of soft sounds diminishes throughout the frequency range (see page 414). In addition, responsiveness to startling noises lessens, and discriminating complex tone patterns becomes harder (Wettstein & Wahl, 2016). Although hearing loss has less impact on self-care than vision loss, it affects safety and enjoyment of life. In the din of city traffic, 80-year-old Ruth didn't always correctly interpret warnings, whether spoken ("Watch it, don't step out yet") or nonspoken (the beep of a horn). And when she turned up the radio or television volume, she sometimes missed the ring of the telephone or a knock at the door. As hearing declines, older people report lower self-efficacy, more loneliness and depressive symptoms, and a smaller social network than their normally hearing peers (Kramer et al., 2002; Mikkola et al., 2015). Of all hearing difficulties, the age-related decline in speech perception has the greatest impact on life satisfaction. After age 70, ability to detect the content and emotionally expressive features of conversation declines, especially in noisy settings (Gosselin & Gagne, 2011). Although Ruth used problem-centered coping to increase her chances of hearing conversation, she wasn't always successful. Because aging adults with hearing loss frequently misunderstand verbal communication, others may conclude they are mentally impaired. Those with hearing loss, as well as those who are visually impaired, do obtain lower scores on tests of executive function and memory (Li & Bruce, 2016). The effort they must devote to perceiving information likely detracts from other cognitive processes needed to perform the tasks. Yet an investigation that followed several thousand older people for up to 15 years revealed that the presence of hearing or visual impairments did not predict cognitive declines, once other factors linked to cognitive functioning (such as age, educational attainment, and chronic illnesses) were controlled (Hong et al., 2016). Assuming that older adults who hear or see poorly are mentally deficient is a mistaken, negative stereotype of aging. Most older people do not suffer from hearing loss great enough to disrupt their daily lives until after age 85. For those who do, compensating with a hearing aid and using an assistive listening device at lectures, movies, and theater performances are helpful. Furthermore, recall from Chapter 4 that beginning at birth, our perception is intermodal. By attending to facial expressions, gestures, and lip movements, older adults can use vision to help interpret the spoken word.

Life Expectancy

Dramatic gains in average life expectancy—the number of years that an individual born in a particular year can expect to live, starting at any age—provide powerful support for the multiplicity of factors considered in previous chapters that slow biological aging, including improved nutrition, medical treatment, sanitation, and safety. Recall from Chapter 1 that in 1900, life expectancy was just under 50 years; in the United States today, it is 78.8—76 for U.S. men and 81 for women. A major factor in this extraordinary gain is a steady decline in infant mortality (see Chapter 3), but death rates among adults have decreased as well, due mostly to advances in medical treatment (Wilmot et al., 2016).

Vision in late adulthood

In Chapter 15, we noted that structural changes in the eye make it harder to focus on nearby objects, see in dim light, and perceive color. In late adulthood, vision diminishes further. The cornea (clear covering of the eye) becomes more translucent and scatters light, which blurs images and increases sensitivity to glare. The lens continues to yellow, leading to further impairment in color discrimination. The number of individuals with cataracts—cloudy areas in the lens, resulting in foggy vision and (without surgery) eventual blindness—increases tenfold from middle to late adulthood, affecting 25 percent of people in their seventies and 50 percent of those in their eighties (Owsley, 2011; Sörensen, White, & Ramchandran, 2016). Besides biological aging, heredity, sun exposure, cigarette smoking, alcohol consumption, and certain diseases (such as hypertension and diabetes) increase the risk of cataracts (Thompson & Lakhani, 2015). Fortunately, removal of the lens and replacement with an artificial lens implant is highly successful in restoring vision. Impaired eyesight in late adulthood largely results from a reduction in light reaching the retina and from cell loss in the retina and optic nerve (refer again to Chapter 15). Dark adaptation—moving from a brightly lit to a dim environment, such as a movie theater—becomes harder. A decline in binocular vision (the brain's ability to combine images received from both eyes) makes depth perception less reliable. And visual acuity (fineness of discrimination) worsens, dropping sharply after age 70 (Owsley, 2011). When light-sensitive cells in the macula, or central region of the retina, break down, older adults may develop macular degeneration, in which central vision blurs and gradually is lost. Macular degeneration is the leading cause of blindness among older adults. About 10 percent of 65- to 74-year-olds, and 30 percent of 75- to 85-year-olds, have symptoms. If diagnosed early, macular degeneration can sometimes be treated with laser therapy. As with cataracts, heredity (including several identified genes) increases risk, especially when combined with cigarette smoking or obesity (Schwartz et al., 2016; Wysong, Lee, & Sloan, 2009). Atherosclerosis also contributes by constricting blood flow to the retina. Protective factors include regular, brisk physical activity and a diet emphasizing fish high in omega-3 fatty acids, which promote cardiovascular health, and fruits and vegetables high in vitamins A, C, E, and carotenoids (yellow and red plant pigments), which help shield cells in the macula from toxic levels of free radicals (Broadhead et al., 2015). When vision loss is extensive, it can affect leisure pursuits and be very isolating. Because of her poor vision, Ruth could no longer enjoy movies, playing bridge, or working crossword puzzles, and she depended on others for help with housekeeping and shopping. But even among people ages 85 and older, only 30 percent experience visual impairment severe enough to interfere with daily living (U.S. Census Bureau, 2014). For many, however, reduced vision goes undetected.

Language Processing in late adulthood

Language and memory skills are closely related. In language comprehension (understanding the meaning of spoken or written prose), we recollect what we have heard or read without conscious awareness. Like implicit memory, language comprehension changes little in late life, as long as conversational partners do not speak too quickly and older adults are given enough time to process written text accurately. Older readers make a variety of adjustments to ensure comprehension, such as devoting more processing time to new concepts than younger readers do, pausing more often to integrate information, and making good use of story organization to help them recall both main ideas and details. Those who have invested more time in reading and other literacy activities over their lifetimes display faster and more accurate reading comprehension (Payne et al., 2012; Stine-Morrow & Payne, 2016). They benefit from years of greater practice at this highly skilled activity. Two aspects of language production show age-related losses. The first is retrieving words from long-term memory. When conversing with others, Ruth and Walt sometimes had trouble finding the right words to convey their thoughts—even well-known words they had used many times in the past. Consequently, their speech contained more pronouns and other unclear references than it did at younger ages (Kemper, 2015). And compared to younger people, they more often reported a tip-of-the-tongue state—certainty that they knew a word accompanied by an inability to produce it. Second, planning what to say and how to say it in everyday conversation is harder in late adulthood. As a result, Walt and Ruth displayed slightly more hesitations, false starts, word repetitions, and sentence fragments as they aged. Their statements were also less grammatically complex and less well-organized than before (Kemper, 2016). As with memory, older adults develop compensatory techniques for their language production problems. For example, they speak more slowly so they can devote more effort to retrieving words and organizing their thoughts. Sacrificing efficiency for greater clarity, they use more sentences, but shorter ones, to convey their message (Griffin & Spieler, 2006). As older people monitor their word-retrieval failures and try hard to overcome them, they more often resolve tip-of-the-tongue states than younger people do (Schwartz & Frazier, 2005). Most aspects of language production, including its content, grammatical correctness, and pragmatics (social appropriateness), are unaffected by aging. And aging adults are advantaged in narrative competence. In telling a story, they draw on their extensive life experience, constructing elaborate, hierarchically organized episodes with rich information about a main character's goals, actions, and motivations and with summarizing references to the story's contemporary significance (Kemper et al., 1990). As a result, listeners tend to prefer older adults' stories to those of young people.

Nervous system in late adulthood

On a routine office visit, 80-year-old Ruth told her doctor, "I think I might be losing my mind. Yesterday, I forgot the name of the family who just moved in next door. And the day before, I had trouble finding the right words to explain to a delivery service how to get to my house." "Ruth, everyone forgets those sorts of things from time to time," Dr. Wiley reassured her. "When we were young and had a memory lapse, we thought little about it. Now, when we do the same thing, we attribute it to having 'a senior moment,' and we worry." Aging of the central nervous system affects a wide range of complex activities. Although brain weight declines throughout adulthood, brain-imaging research and after-death autopsies reveal that the loss becomes greater starting in the fifties and amounts to as much as 5 to 10 percent by age 80, due to withering of the myelin coating on neural fibers, loss of synaptic connections, death of neurons, and enlargement of ventricles (spaces) within the brain (Fiocco, Peck, & Mallya, 2016; Rodrigue & Kennedy, 2011). Neuron loss occurs throughout the cerebral cortex but at different rates among different regions. In longitudinal studies, the frontal lobes, especially the prefrontal cortex (responsible for executive function and strategic thinking), and the corpus callosum (which connects the two cortical hemispheres), tended to show the greatest shrinkage (Fabiani, 2012; Lockhart & DeCarli, 2014). The cerebellum (which controls balance and coordination and supports cognitive processes) and the hippocampus (involved in memory and spatial understanding) also lose neurons (Fiocco, Peck, & Mallya, 2016). And EEG measures reveal gradual slowing and reduced intensity of brain waves—signs of diminished efficiency of the central nervous system (Kramer, Fabiani, & Colcombe, 2006). But brain-imaging research reveals wide individual differences in the extent of these losses, which are moderately associated with declines in cognitive functioning (Ritchie et al., 2015). And the brain can overcome some decline. In several studies, growth of neural fibers in the brains of older adults unaffected by illness took place at the same rate as in middle-aged people. Aging neurons established new synapses after other neurons had degenerated (Flood & Coleman, 1988). Furthermore, the aging cerebral cortex can, to a limited degree, generate new neurons (Snyder & Cameron, 2012). And fMRI evidence reveals that compared with younger adults, older people who do well on memory and other cognitive tasks show more widely distributed activity across areas of the cerebral cortex (Fabiani, 2012; Reuter-Lorenz & Cappell, 2008). This suggests that one way older adults compensate for neuron loss is to call on additional brain areas to support cognitive processing. The autonomic nervous system, involved in many life-support functions, also performs less well, placing older adults at risk during heat waves and cold spells. Because of decreased sweating, tolerance for hot weather declines. And during cold exposure, body core temperature rises less readily (Blatteis, 2012). The autonomic nervous system also releases higher levels of stress hormones into the bloodstream than it did earlier, perhaps to arouse body tissues that have become less responsive to these hormones (Whitbourne, 2002). As we will see, this change may contribute to decreased immunity and to sleep problems.

Explicit versus Implicit Memory

"Ruth, you know that movie we saw—the one with the little 5-year-old boy who did such a wonderful acting job. I'd like to suggest it to Dick and Goldie. But what was it called?" asked Walt. "I can't think of it, Walt. We've seen a few movies lately. Which theater was it at? Who'd we go with? Tell me more about the little boy—maybe it'll come to me." Although everyone occasionally has memory failures like this, aging adults find diverse aspects of episodic recall increasingly challenging. When Ruth and Walt watched the movie, their slower cognitive processing meant that they retained fewer details. And because their working memories could hold less at once, they attended poorly to context—where they saw the movie and who went with them (Zacks & Hasher, 2006). When we try to remember, context serves as an important retrieval cue. These memory difficulties mean that older people sometimes cannot distinguish an imagined event from one they actually experienced (Rybash & Hrubi-Bopp, 2000). They find it harder to recall the source of information—which member of their bridge club made a certain statement, to whom and on which occasion they previously told a certain joke or story, and (in laboratory research) within which of two 10-word lists they had just studied particular words had appeared (Wahlheim & Huff, 2015). Temporal memory—recall of the order in which events occurred or how recently they happened—suffers as well (Hartman & Warren, 2005; Rotblatt et al., 2015). Older adults' limited working memories increase the likelihood of another type of episodic memory difficulty: They may, for example, travel from the den to the kitchen intending to get something but then not recall what they intended to get. When the context in which they formed the memory intention (the den) differs from the retrieval context (the kitchen), they often experience memory lapses (Verhaeghen, 2012). Once they return to the first context (the den), it serves as a strong cue for their memory intention because that is where they first encoded it, and they say, "Oh, now I remember why I went to the kitchen!" A few days later, when Ruth saw a TV ad for the movie whose title she had forgotten, she recognized its name immediately. Recognition—a fairly automatic type of memory that demands little mental effort—suffers less than recall in late adulthood because a multitude of environmental supports for remembering are present. Age-related declines in memory are greatest on explicit memory tasks, which require controlled, strategic processing (Hoyer & Verhaeghen, 2006). Consider another automatic form of memory: implicit memory, or memory without conscious awareness. In a typical implicit memory task, you would be shown a list of words, then asked to fill in a word fragment (such as t- -k). You would probably complete the sequence with a word you had just seen (task) rather than another word (took or teak). Without trying to do so, you would engage in recall. Age differences in implicit memory are much smaller than in explicit memory. Memory that depends on familiarity rather than on conscious use of strategies is better preserved in old age (Koen & Yonelinas, 2013; Ward, Berry, & Shanks, 2013). This helps explain why semantic memory—recall of vocabulary and general information, which are mostly well-learned and highly familiar—declines far less, and does so at later ages, than recall of everyday experiences (Small et al., 2012). The episodic memory problems aging adults report—for names of people, places where they put important objects, directions for getting from one place to another, and (as we will see) appointments and medication schedules—all place high demands on their more limited working memories and on other executive processes.

Assistive Technology

A rapidly expanding assistive technology, or array of devices that permit people with disabilities to improve their functioning, is available to help older people cope with physical declines. Computers and smart devices are the greatest sources of these innovative products (Czaja, 2016). Smartphones that respond to voice commands to make and answer calls help those with visual or motor difficulties. For older people who take multiple medications, a tiny computer chip called a "smart cap" can be placed on medicine bottles that beeps periodically as a reminder to take the drug and tracks how many and at what time pills have been taken. Smart watches and smart clothing can monitor diverse health indicators, improving prevention, early detection, and treatment. These devices can also recognize emergency situations, including falls, and summon help automatically. Robots are available that assist older adults with diverse tasks, such as retrieving objects, reading documents, and doing routine housework. Architects have also designed homes that can adapt to changing physical needs—equipping them with movable walls that expand and contract, plumbing that enables a full bathroom to be added on the main floor, and "smart-home" technologies that promote safety and mobility, such as sensors in floors that activate room lights when an older person gets up at night and alarm systems that detect falls. Use of assistive devices slows physical declines and reduces the need for personal caregiving (Agree, 2014; Wilson et al., 2009). Do older people with disabilities regard some technologies as invasions of privacy? The majority weigh privacy concerns against potential benefits—saying, for example, "If this device would keep me independent longer, I wouldn't mind" (Brown, Rowles, & McIlwain, 2016). Sustaining an effective person-environment fit, or match between older people's current capabilities and the demands of their living environments, enhances psychological well-being (Lin & Wu, 2014). Yet U.S. government-sponsored health-care coverage is largely limited to essential medical equipment. Sweden's health-care system, in contrast, covers many assistive devices that promote function and safety, and its building code requires that new homes include a full bathroom on the main floor (Swedish Institute, 2016). In this way, Sweden strives to help older adults remain as independent as possible.

Wisdom in late adulthood

A wealth of life experience underlies another capacity believed to reach its height in old age: wisdom. When researchers ask people to describe wisdom, most mention breadth and depth of practical knowledge, ability to reflect on and apply that knowledge in ways that make life more bearable and worthwhile; emotional maturity, including the ability to listen patiently and empathetically and give sound advice; and altruistic creativity that contributes to humanity and enriches others' lives. One group of researchers summed up the multiple cognitive and personality traits that make up wisdom as "expertise in the conduct and meaning of life" (Baltes & Smith, 2008; Baltes & Staudinger, 2000, p. 124; Kunzmann, 2016). During her college years, Ruth and Walt's granddaughter Marci telephoned with a pressing personal dilemma. Ruth's advice reflected the features of wisdom just mentioned. After her boyfriend Ken moved to another city to attend medical school, Marci, unsure whether her love for Ken would endure, had begun dating another student. "I can't stand being pulled in two directions," she exclaimed. "I'm thinking of calling Ken and telling him about Steve." "This is not a good time, Marci," Ruth advised. "You'll break Ken's heart before you've had a chance to size up your feelings for Steve. And you said Ken's taking some important exams in two weeks. If you tell him now and he's distraught, it could affect the rest of his life." Wisdom—whether applied to personal problems or to community, national, and international concerns—requires the "pinnacle of insight into the human condition" (Baltes & Staudinger, 2000; Birren, 2009). Not surprisingly, cultures around the world assume that age and wisdom go together. In village and tribal societies, the most important social positions, such as chieftain and shaman (religious leader), are reserved for the old. Similarly, in industrialized nations, older adults are chief executive officers of large corporations, high-level religious leaders, members of legislatures, and supreme court justices. According to an evolutionary view, the genetic program of our species grants health, fitness, and strength to the young. Culture tames this youthful advantage in physical power with the insights of the old, ensuring balance and interdependence between generations (Csikszentmihalyi & Nakamura, 2005). In the most extensive research to date on development of wisdom, adults ranging in age from 20 to 89 responded to uncertain real-life situations—for example, what to consider and do if a good friend is about to commit suicide or if, after reflecting on your life, you discover that you have not achieved your goals (Staudinger, 2008; Staudinger, Dörner, & Mickler, 2005). Responses were rated for five ingredients of wisdom: Knowledge about fundamental concerns of life, including human nature, social relations, and emotions Effective strategies for applying that knowledge to making life decisions, handling conflict, and giving advice A view of people that considers the multiple demands of their life contexts A concern with ultimate human values, such as the common good, as well as respect for individual differences in values Awareness and management of the uncertainties of life—that many problems have no perfect solution Results revealed that age is no guarantee of wisdom. A small number of adults of diverse ages ranked among the wise. But type of life experience made a difference. People in human-service careers who had extensive training and practice in grappling with human problems tended to attain high wisdom scores. Other high-scorers held leadership positions (Staudinger, 1996; Staudinger & Glück, 2011). And when age and relevant life experiences were considered together, more older than younger people scored in the top 20 percent. In addition, having faced and overcome adversity appears to be an important contributor to late-life wisdom (Ardelt & Ferrari, 2015). In one study, low- and moderate-income older adults nominated by aging-services providers as wise reported deriving valuable life lessons from coping with hardships, including patience, perseverance, forgiveness, and willingness to accept advice and support from others (Choi & Landeros, 2011). Compared to their agemates, older adults with the cognitive, reflective, and emotional (compassionate) qualities that make up wisdom are better educated, forge more positive relations with others, and score higher on the personality dimension of openness to experience (Kramer, 2003). Wisdom is also linked to personal growth (continued desire to expand as a person), sense of autonomy and purpose in life (enabling resistance to social pressures to think and act in certain ways), generativity, and favorable adjustment to aging (Ardelt & Ferrari, 2015; Wink & Staudinger, 2016). Wise older people seem to flourish, even when faced with physical and cognitive challenges.

Diabetes

After a meal, the body breaks down the food, releasing glucose (the primary energy source for cell activity) into the bloodstream. Insulin, produced by the pancreas, keeps the blood concentration of glucose within set limits by stimulating muscle and fat cells to absorb it. When this balance system fails, either because not enough insulin is produced or because body cells become insensitive to it, type 2 diabetes (otherwise known as diabetes mellitus) results. Over time, abnormally high blood glucose damages the blood vessels, increasing the risk of heart attack, stroke, circulatory problems in the legs (which impair balance and gait), and injury to the eyes, kidneys, and nerves. Impaired glucose tolerance also accelerates degeneration of neurons and synapses (Petrofsky, Berk, & Al-Nakhli, 2012). In several longitudinal studies, diabetes was associated with more rapid cognitive declines in older people and an elevated risk of dementia, especially Alzheimer's disease—an association we will soon revisit when we take up Alzheimer's (Baglietto-Vargas et al., 2016; Cheng et al., 2012). From middle to late adulthood, the incidence of type 2 diabetes nearly doubles; it affects one-fourth of Americans ages 65 and older (Centers for Disease Control and Prevention, 2014c). Diabetes runs in families, suggesting that heredity is involved. But inactivity and abdominal fat deposits greatly increase the risk. Higher rates of type 2 diabetes—exceeding 30 percent—are found among African-American, Mexican-American, and Native-American aging adults for both genetic and environmental reasons, including high-fat diets and obesity associated with poverty. Treating type 2 diabetes requires a carefully controlled diet and regular exercise, which promote weight loss and glucose reabsorption. In many people with recent disease onset (less than one year), sustaining these behaviors partially or completely reverses the course of the illness (Ades, 2015).

Remote Memory

Although older people often say that their remote memory, or very long-term episodic recall, is clearer than their memory for recent events, research does not support this conclusion. To investigate remote recall, researchers probe autobiographical memory, or recall of personally meaningful events, such as what you did on your first date or how you celebrated your college graduation. Sometimes participants varying in age are given a series of words (such as book, machine, sorry, surprised) and asked to report a personal memory cued by each. Or they may simply be asked to describe important life events, noting the age at which each occurred. Older adults recall both remote and recent events more often than intermediate events, with recent events mentioned most frequently in word-cue studies. The important-memories method evokes a larger number of remote events because it induces people to search their memories thoroughly for significant experiences (see Figure 17.5). Among remote events recalled, most happened between ages 10 and 30—a period of heightened autobiographical memory called the reminiscence bump (Janssen, Rubin, & St. Jacques, 2011; Koppel & Berntsen, 2014; Koppel & Rubin, 2016). The reminiscence bump is evident in the autobiographical recall of older adults from diverse cultures—Bangladesh, China, Japan, Turkey, and the United States (Conway et al., 2005; Demiray, Gülgöz, & Bluck, 2009). Why are adolescent and early adulthood experiences retrieved more readily than those of middle adulthood? Youthful events occur during a period of rapid life change filled with novel experiences that stand out from the humdrum of daily life. Adolescence and early adulthood are also times of identity development, when many personally significant experiences occur. Furthermore, the reminiscence bump characterizes emotionally positive, but not negative, memories. Culturally shared, important life events—school proms, graduations, marriage, birth of children—are usually positive and cluster earlier in life (Dickson, Pillemer, & Bruehl, 2011). Finally, the richness of older adults' remote autobiographical memories—mentions of people, objects, places, times, feelings, and other details—modestly exceeds that of younger people (Gardner, Mainetti, & Ascoli, 2015). Important early life events are usually recalled many times throughout life, on one's own and in elaborative conversations with others, which strengthen them.

Life Expectancy in Late Adulthood

Although poverty-stricken groups lag behind the economically advantaged, the proportion of older adults has risen dramatically in the industrialized world. Because of aging baby boomers, older adults are projected to rise from 15 percent of the U.S. population today to 20 percent by 2030. Among older Americans, the fastest-growing segment is the 85-and-older group, which currently makes up nearly 2 percent of the U.S. population. By 2050, they are expected to swell to more than double their current number (U.S. Department of Health and Human Services, 2015e). Americans reaching age 65 in the early twenty-first century can look forward, on average, to 19 more years of life. Although women outnumber men by a greater margin at older ages, women's advantage in life expectancy shrinks with age—in the United States, from 3 years at age 65 to 1 year at age 85. Over age 100, the gender difference disappears (Arias, 2015). Similarly, differences in rates of chronic illness and in life expectancy between European Americans and African Americans lessen with age. After age 80, a life expectancy crossover occurs—surviving African Americans live longer than members of the white majority (Masters, 2012; Roth et al., 2016; Sautter et al., 2012). Researchers speculate that among men and economically disadvantaged African Americans, only the biologically sturdiest survive into very old age. Throughout this book, we have seen that genetic and environmental factors jointly affect aging. With respect to heredity, identical twins typically die within 3 years of each other, whereas fraternal twins of the same sex differ by more than 6 years. Also, longevity runs in families. When both parents survive to age 70 or older, the chances that their children will live to 90 or 100 are double that of the general population (Cevenini et al., 2008; Hayflick, 1994; Mitchell et al., 2001). At the same time, evidence from twin studies suggests that once people pass 75 to 80 years, the contribution of heredity to length of life decreases in favor of environmental factors—a healthy diet; normal body weight; regular exercise; little or no tobacco, alcohol, and drug use; an optimistic outlook; low psychological stress; and social support (Yates et al., 2008; Zaretsky, 2003). As the Biology and Environment box on page 462 reveals, the study of centenarians—people who cross the 100-year mark—offers special insights into how biological, psychological, and social influences work together to promote a long, satisfying life. Perhaps you are wondering: For humans, what is the maximum lifespan, or species-specific biological limit to length of life (in years), corresponding to the age at which the oldest known individual died? As the Biology and Environment box on page 462 indicates, the oldest verified age is 122 years. Does this figure actually reflect the upper bound of human longevity, or can it be extended? At present, scientists disagree on the answer. But the controversy raises another issue: Should maximum lifespan be increased as far as possible? Many people respond that the important goal is not just quantity of life, but quality—doing everything possible to extend healthy life expectancy. Most experts agree that only after reducing the high rates of preventable illness and disability among low-SES individuals and wiping out age-related diseases should we invest in lengthening the maximum lifespan.

Immune system in late adulthood

As the immune system ages, T cells, which attack antigens (foreign substances) directly, become less numerous and effective (see Chapter 13, page 360). In addition, the immune system is more likely to malfunction by turning against normal body tissues in an autoimmune response. A less competent immune system reduces the effectiveness of available vaccines and increases the risk of a variety of illnesses—in addition to infectious diseases (such as the flu), cardiovascular disease, certain forms of cancer, and various autoimmune disorders, such as rheumatoid arthritis and diabetes (Herndler-Brandstetter, 2014). Although older adults vary greatly in immunity, most experience some loss, ranging from partial to profound (Ponnappan & Ponnappan, 2011). The strength of the aging person's immune system seems to be a sign of overall physical vigor. Certain immune indicators, such as high T cell activity, predict better physical functioning and survival over the next two years in very old people (Moro-García et al., 2012; Wikby et al., 1998). With age, the autonomic nervous system releases higher levels of stress hormones into the bloodstream. As the immune response declines with age, stress-induced susceptibility to infection rises dramatically (Archer et al., 2011). A healthy diet and exercise help protect the immune response in old age, whereas obesity aggravates the age-related decline.

Unintentional Injuries

At ages 65 and older, the death rate from unintentional injuries is at an all-time high—more than twice as great as in adolescence and early adulthood. Motor vehicle collisions and falls are largely responsible.

Arthritis

Beginning in her late fifties, Ruth felt a slight morning stiffness in her neck, back, hips, and knees. In her sixties, she developed bony lumps on the end joints of her fingers. As the years passed, she experienced joint pain, swelling, and some loss of flexibility. Arthritis, a condition of inflamed, painful, stiff, and sometimes swollen joints and muscles, becomes more common in late adulthood. It occurs in several forms. Ruth has osteoarthritis, the most common type, which involves deteriorating cartilage on the ends of bones of frequently used joints. Otherwise known as "wear-and-tear arthritis" or "degenerative joint disease," it is one of the few age-related disabilities in which years of use make a difference. Although a genetic proneness exists, the disease usually does not appear until the forties or fifties. In frequently used joints, cartilage on the ends of the bones, which reduces friction during movement, gradually deteriorates. Or obesity places abnormal pressure on the joints and damages cartilage. Almost all older adults show some osteoarthritis on X-rays, although wide individual differences in severity exist (Baker & Mingo, 2016). About 45 percent of U.S. men over age 65 have been diagnosed with the disease, 20 percent of whom experience disability. Among women ages 65 and older, the disease incidence is higher, at 55 percent, and so is the rate of disability among diagnosed individuals, at 25 percent (Hootman et al., 2016). Osteoarthritis is the most common cause of surgical hip and knee replacements in older adults. Unlike osteoarthritis, which is limited to certain joints, rheumatoid arthritis involves the whole body. An autoimmune response leads to inflammation of connective tissue, particularly the membranes that line the joints, resulting in overall aching, inflammation, and stiffness. Tissue in the cartilage tends to grow, damaging surrounding ligaments, muscles, and bones. The result is deformed joints and often serious loss of mobility. Sometimes other organs, such as the heart and lungs, are affected (Goronzy, Shao, & Weyand, 2010). Worldwide, about ½ to 1 percent of older adults have rheumatoid arthritis, more often women than men. Although rheumatoid arthritis can strike at any age, it increases after age 60. Twin studies support a strong hereditary contribution. Presence of certain genes heightens disease risk, possibly by triggering a late-life defect in the immune system (Frisell, Saevarsdottir, & Askling, 2016; Yarwood et al., 2015). However, identical twins differ widely in disease severity, indicating that environment makes a difference. So far, cigarette smoking is the only confirmed lifestyle influence (Di Giuseppe et al., 2014). Early treatment with powerful anti-inflammatory medications helps slow progression of rheumatoid arthritis. Managing arthritis requires a balance of rest when the disease flares, pain relief, and physical activity. Regular aerobic exercise and strength training lessen pain and improve physical functioning (Semanik, Chang, & Dunlop, 2012). With proper analgesic medication, joint protection, lifestyle changes, and surgery to replace badly damaged hip or knee joints, many people with either form of the illness lead long, productive lives.

Misdiagnosed and Reversible Dementia

Careful diagnosis of dementia is crucial because other disorders can be mistaken for it. And some forms of dementia can be treated and a few reversed. Depression is the disorder most often misdiagnosed as dementia. Between 1 and 5 percent of people over age 65 are severely depressed—a rate lower than for young and middle-aged adults. As we will see in Chapter 18, however, depression rises with age, is often related to physical illness and pain, and can lead to cognitive deterioration. However, U.S. older adults often do not receive the mental health services they need—partly because Medicare offers reduced coverage for treating mental health problems and partly because doctors rarely refer older people for mental health services (Hinrichsen, 2016). These circumstances increase the chances that depression will deepen and be confused with dementia. The older we get, the more likely we are to be taking drugs that may have side effects resembling dementia. For example, some medications for coughs, diarrhea, and nausea inhibit the neurotransmitter acetylcholine, leading to Alzheimer's-like symptoms. In addition, some diseases can cause temporary memory loss and mental symptoms (Grande et al., 2016; Tveito et al., 2016). Treating the underlying illness relieves the problem. Finally, environmental changes and social isolation can trigger mental declines (Hawton et al., 2011). When supportive ties are restored, cognitive functioning usually bounces back.

Sensory Systems in late adulthood

Changes in sensory functioning become increasingly noticeable in late life. Older adults see and hear less well, and their taste, smell, and touch sensitivity also decline. As Figure 17.2 shows, in late life, hearing impairments are more common than visual impairments. Extending trends in middle adulthood, more women than men report being visually impaired, more men than women hearing impaired.

Physical Disabilities in late adulthood

Compare the death rates shown in Figure 17.4 with those in Figure 15.3 on page 419. You will see that illness and disability climb as the end of the lifespan approaches. Heart disease and cancer remain the leading causes of death, increasing dramatically from mid- to late life. As before, death rates from heart disease and cancer are higher for men than for women (Heron, 2015). Respiratory diseases, which rise sharply with age, are the third most common cause of death among older adults. Among such diseases is emphysema, caused by extreme loss of elasticity in lung tissue, with most cases resulting from long-term cigarette smoking. Stroke and Alzheimer's disease follow; both are unique in being more prevalent among women, largely because women live longer. Stroke occurs when a blood clot blocks a blood vessel or a blood vessel hemorrhages in the brain, causing damage to brain tissue. It is a major cause of late-life disability and, after age 75, death. Alzheimer's disease, the leading cause of dementia, also rises sharply with age; we will consider it in-depth shortly. Other diseases are less frequent killers, but they limit older adults' ability to live fully and independently. We have already noted the increase after age 65 in macular degeneration, which severely impairs vision and leads to blindness (see page 463). Osteoporosis, discussed in Chapter 15, continues to rise in late adulthood. Yet another bone disorder—arthritis—adds to the physical limitations of many older people. And type 2 diabetes and unintentional injuries also multiply in late adulthood. In the following sections, we take up these last three conditions. Finally, an important point must be kept in mind as we discuss physical and mental disabilities of late adulthood: That these conditions are strongly related to age does not mean that they are entirely caused by aging. To clarify this distinction, experts distinguish between primary aging (another term for biological aging), or genetically influenced declines that affect all members of our species and take place even in the context of overall good health, and secondary aging, declines due to hereditary defects and negative environmental influences, such as poor diet, lack of exercise, disease, substance abuse, environmental pollution, and psychological stress. Throughout this book, we have seen that it is difficult to distinguish primary from secondary aging. Undoubtedly you have, at one time or another, encountered frail older adults—people with extreme infirmity who display wasted muscle mass and strength, weight loss, severe mobility problems, and perhaps cognitive impairment. Frailty involves weakened functioning of diverse organs and body systems, which profoundly interferes with everyday competence and leaves older people highly vulnerable in the face of infection, extremely hot or cold weather, or injury (Moorehouse & Mallery, 2016). Although primary aging contributes to frailty, researchers agree that secondary aging plays a larger role, through genetic disorders, unhealthy lifestyle (including obesity and sedentary behavior), and chronic disease (Fried et al., 2009; Song et al., 2015). The serious conditions we are about to discuss are major sources of late-life frailty.

Variations in Life Expectancy

Consistent group differences in life expectancy underscore the joint contributions of heredity and environment to biological aging. In countries around the globe, women outlive men, by an average of five years (Rochelle et al., 2015). The protective value of females' extra X chromosome (see Chapter 2), along with their reduced risk taking and physical aggression (Chapters 6 and 8), are believed to be responsible. Yet since the 1990s, the gender gap in life expectancy has narrowed in industrialized nations (Deeg, 2016). Because men are at higher risk for disease and early death, they reap somewhat larger generational gains from positive lifestyle changes and new medical discoveries. Life expectancy varies substantially with SES. As education and income increase, so does length of life (Chetty et al., 2016; Whitfield, Thorpe, & Szanton, 2011). In the United States, the gap in life expectancy at birth between the wealthiest and the poorest individuals is 14½ years for men and 10 years for women. SES also accounts for the 2- to 3-year advantage in life expectancy for European-American over African-American adults ages 65 and older (Centers for Disease Control and Prevention, 2016b). As noted in Chapter 13, stressful life events, wide-ranging unhealthy behaviors, jobs with health risks, and weak social supports are associated with low SES. Length of life—and, even more important, quality of life in old age—can be predicted by a country's health care, housing, and social services, along with lifestyle factors. When researchers estimate average healthy life expectancy, the number of years a person born in a particular year can expect to live in full health, without disease or injury, Japan ranks first, with the United States falling below the overwhelming majority of industrialized nations (see Figure 17.1). Japan's leading status has been attributed to its low rates of obesity and heart disease (linked to its low-fat diet) along with its favorable health-care policies. In developing nations with widespread poverty, malnutrition, disease, and armed conflict, average life expectancy hovers around 55 years. And healthy life expectancy is reduced by three to four decades compared with the industrialized world—for example, only 48 years in Afghanistan, 47 in Sierra Leone, and 28 in Haiti, where overall health recently declined because of the 2010 catastrophic earthquake (Salomon et al., 2012).

Physical Development in late adulthood

Do you know older adults who "seem young" or "seem old" for their age? In using these descriptors, we acknowledge that chronological age is an imperfect indicator of functional age, or actual competence and performance. Because people age biologically at different rates, some 80-year-olds appear younger than many 65-year-olds. Also, recall from Chapter 13 that within each person, change differs across parts of the body. For example, Ruth became infirm physically but remained active mentally, whereas Ida, though physically fit for her age, found it hard to converse with others, keep appointments, or complete familiar tasks. So much variation exists between and within individuals that researchers have not yet identified any single biological measure that predicts the overall rate at which a person will age. But we do have estimates of how much longer older adults can expect to live, and our knowledge of factors affecting longevity in late adulthood has increased rapidly.

Cognitive Interventions in late adulthood

For most of late adulthood, cognitive declines are gradual. If plasticity of development is possible, then interventions that train older people in cognitive strategies should at least partially reverse the age-related declines we have discussed. Older adults' relatively well-preserved metacognition is a powerful asset in training efforts. Most, for example, are aware of memory declines and know they must take extra steps to ensure recall of important information (Blake & Castel, 2016). Their impressive metacognitive understanding is also evident in the wide-ranging techniques they devise to compensate for everyday cognitive challenges. The Adult Development and Enrichment Project (ADEPT) is the most extensive cognitive intervention program conducted to date (Schaie, 2005). By using participants in the Seattle Longitudinal Study (see Chapter 15, pages 426-427), researchers were able to do what no other investigation has done: assess the effects of cognitive training on long-term development. Intervention began with adults over age 64, some of whom had maintained their scores on tests of two mental abilities (inductive reasoning and spatial orientation) over the previous 14 years and others who had shown declines. After just five one-hour training sessions in one of two types of mental test items, two-thirds of participants improved their performance on the trained skill. Gains for decliners were dramatic: Forty percent returned to the level at which they had been functioning 14 years earlier! A follow-up after 7 years revealed that although scores dropped somewhat, participants remained advantaged in their trained skill over agemates trained in the other ability. Finally, "booster" training at this time led to further gains, although these were smaller than the earlier gains. In another large-scale intervention study called ACTIVE (Advanced Cognitive Training for Independent and Vital Elderly), more than 2,800 65- to 84-year-olds were randomly assigned to a 10-session training program focusing on one of three abilities—speed of processing, memory strategies, or reasoning—or to a no-intervention control group. Again, trained older adults showed an immediate advantage in the trained skill over controls that was still evident—though smaller in magnitude—at a 5-year follow-up and, for speed and reasoning, at a 10-year follow-up. Furthermore, 5 and 10 years after intervention, cognitive training was associated with reduced declines in ability to perform IADLs—outcomes strongest for the speed-of-processing group and, secondarily, the reasoning group (Rebok et al., 2014; Wolinsky et al., 2006). Speed gains also predicted other aspects of everyday functioning, including more favorable self-rated health, reduced depressive symptoms, fewer at-fault motor vehicle collisions, and longer time to giving up driving (Tennstedt & Unverzagt, 2013). The investigators speculated that speed-of-processing training induces a broad pattern of brain activation, affecting many regions. Clearly, many cognitive skills can be enhanced in old age. Small-scale studies targeting executive function that provide intensive training over multiple weeks show promising improvements, especially on working-memory tasks. In some research, gains lasted for several months following intervention and transferred to other cognitive skills, such as sustained attention and episodic memory (Brehmer, Westerberg, & Bäckman, 2012; Grönholm-Nyman, 2015). A vital goal is to shift intervention from the laboratory to the community, weaving it into aging adults' recurring experiences. Community programs in the participatory arts—including dance, music, and theater training—yield gains on a broad range of cognitive measures (Noice, Noice, & Kramer, 2014).

Adapting to Physical Changes of Late Adulthood

Great diversity exists in older adults' adaptation to the physical changes of aging. People who are more anxious about growing older monitor their physical state more closely and are more concerned about their appearance (Montepare, 2006). Dick and Goldie took advantage of an enormous industry designed to stave off outward signs of old age, including cosmetics, wigs, and plastic surgery, plus various "anti-aging" dietary supplements, herbal products, and hormonal medications offered by "longevity" clinics—none with any demonstrated benefits and some of them harmful (Olshansky, Hayflick, & Perls, 2004). In contrast, Ruth and Walt were relatively unconcerned about their thinning white hair and wrinkled skin. Their identities were less bound up with their appearance than with their ability to remain active. Most older people sustain a favorable subjective age—say they feel younger than they look and than they actually are (Kleinspehn-Ammerlahn, Kotter-Grühn, & Smith, 2008; Westerhof, 2008). In several investigations, 75-year-olds reported feeling about 15 years younger! At follow-ups from a few years to two decades later, youthful self-evaluation predicted more favorable psychological well-being, better physical health and health behaviors, and slightly longer survival (Keyes & Westerhof, 2012; Westerhof et al., 2014). The most obvious outward signs of aging—graying hair, facial wrinkles, and baldness—bear no relationship to cognitive functioning or to longevity (Schnohr et al., 1998). In contrast, neurological, cardiovascular, respiratory, metabolic, immune-system, and skeletal and muscular health are strongly associated with cognitive performance and both quality and length of later life (Bergman, Blomberg, & Almkvist, 2007; Garcia-Pinillos et al., 2016; Herghelegiu & Prada, 2014; Qui, 2014). Furthermore, people can do more to prevent declines in the functioning of these internal body systems than they can do to prevent gray hair and baldness!

Health, Fitness, and Disability

Health is central to psychological well-being in late life. When researchers ask older adults about possible selves (see Chapter 16, page 439), number of hoped-for physical selves declines with age and number of feared physical selves increases. Nevertheless, because older people compare themselves to same-age peers, the majority rate their health favorably. And aging adults' self-rated health does not decline as much as would be expected on the basis of objective health assessments (French, Sargent-Cox, & Luszcz, 2012; U.S. Department of Health and Human Services, 2015d). As for protecting their health, older adults' sense of self-efficacy is as high as that of young adults and higher than that of middle-aged people. Self-efficacy and optimism about one's health promote continued health-enhancing behaviors (Frazier, 2002; Kubzansky & Boehm, 2016). SES continues to predict physical functioning. African-American and Hispanic older people (one-fifth of whom live in poverty) remain at greater risk for various health problems, including cardiovascular disease, diabetes, and certain cancers. Native-American aging adults are even worse off (Cubanski, Casillas, & Damico, 2015; Mehta, Sudharsanan, & Elo, 2014). The majority are poor, and chronic health conditions—including diabetes, kidney disease, liver disease, tuberculosis, and hearing and vision impairments—are so widespread that in the United States, the federal government grants Native Americans special health benefits. These begin as early as age 45, reflecting a much harder and shorter lifespan. Unfortunately, low-SES and ethnic minority older adults are more likely than their higher-SES and white counterparts to delay or forgo medical treatment (Weech-Maldonado, Pradhan, & Powell, 2014). One reason is cost: On average, U.S. Medicare beneficiaries devote 18 percent of their income to out-of-pocket health-care expenses—a figure that escalates among those with the fewest resources (Noel-Miller, 2015). Another reason is perceived discriminatory treatment by health-care providers, which undermines ethnic minority patients' trust (Guerrero, Mendes de Leon, & Evans, 2015). Furthermore, low-SES and minority older people often do not comply with doctors' directions because they feel less in control of their health and less optimistic that treatment will work. The sex differences noted in Chapter 15 extend into late adulthood: Men are more prone to fatal diseases, women to non-life-threatening disabling conditions. By very old age (80 to 85 and beyond), women are more impaired than men because only the sturdiest men have survived (Deeg, 2016). In addition, with fewer physical limitations, older men are better able to remain independent and to engage in exercise, leisure and volunteer pursuits, and social activities, all of which promote better health. Widespread health-related optimism among older people suggests that substantial inroads into preventing disability can be made even in the last few decades of life. Ideally, as life expectancy extends, we want the average period of diminished vigor before death—especially, the number of months or years of ill-health and suffering—to decrease. This public health goal is called the compression of morbidity. Several large-scale studies indicate that over the past several decades, compression of morbidity has occurred in industrialized nations (Fries, Bruce, & Chakravarty, 2011; Taylor & Lynch, 2011). Medical advances and improved socioeconomic conditions are largely responsible. In addition, the impact of good health habits on postponement of disability is large. In one investigation, researchers followed a large sample of university alumni from their late sixties over the next two decades. In those who were low risk (no risk factors of smoking, obesity, or lack of exercise), disability was delayed by nearly 5 years compared with those who were moderate risk (had one of these risk factors). Compared to high-risk participants (with two or three risk factors), postponement of disability in the low-risk group exceeded 8 years (Chakravarty et al., 2012). Although good health habits lengthened life by about 3½ years, their impact on functional ability was greater. Broad strategies are needed in the developing world, where 70 percent of older people will reside by 2025. In these nations, poverty is rampant, chronic diseases occur earlier, even routine health interventions are unavailable or too costly for many, and most public health programs do not focus on late adulthood (Rinaldo & Ferraro, 2012). As a result, disability rates among older adults are especially high, and as yet, no progress has been made in compression of morbidity.

Factors Related to Cognitive Maintenance and Change

Heritability research suggests a modest genetic contribution to individual differences in cognitive change in late adulthood (Deary et al., 2012). At the same time, a mentally active life is vital for preserving cognitive resources. Above-average education; frequent contact with family members and friends; stimulating work, leisure pursuits, and community participation; and a flexible personality predict higher mental test scores and reduced cognitive decline into advanced old age (Schaie, 2013; Wang et al., 2013). Today's aging adults in industrialized nations are better educated than any previous generation. As more baby boomers enter late adulthood, this trend is expected to continue, forecasting improved preservation of cognitive functions. As noted earlier, health status powerfully predicts older adults' cognitive functioning. Diverse chronic conditions, including cardiovascular disease, diabetes, osteoporosis, and arthritis, are strongly associated with cognitive declines (O'Connor & Kraft, 2013). As people grow older, their cognitive scores show larger fluctuations from one occasion to the next. This rising instability of performance—especially in speed of response—accelerates in the seventies and is associated with worsening cognition, along with neurobiological signs of shrinkage in the prefrontal cortex and deficient brain functioning (Bielak et al., 2010; Lövdén et al., 2012; MacDonald, Li, & Bäckman, 2009). It seems to signal end-of-life brain degeneration. Terminal decline refers to acceleration in deterioration of cognitive functioning prior to death. Some investigations indicate that it is limited to a few aspects of intelligence, others that it occurs generally, across many abilities. Findings also differ greatly in its estimated length—from 1 to 3 to as long as 14 years, with an average of 4 to 5 years (Lövdén et al., 2005; MacDonald, Hultsch, & Dixon, 2011; Rabbitt, Lunn, & Wong, 2008). In several studies, a sharp drop in psychological well-being, including diminished sense of personal control and social participation and increased negative affect, predicted mortality (Gerstorf & Ram, 2013; Schilling, Wahl, & Wiegering, 2013). The downturn is especially steep in people ages 85 and older and is only weakly related to mental deterioration or chronic illnesses. Perhaps different kinds of terminal decline exist—one type arising from disease processes, another reflecting general biological breakdown due to normal aging. What we do know is that an accelerating falloff in cognitive performance or in emotional investment in life is a sign of loss of vitality and impending death.

Physical appearance and mobility in late adulthood

In earlier chapters, we saw that changes leading to an aged appearance are under way as early as the twenties and thirties. Because these occur gradually, older adults may not notice that they look older until the changes have become obvious. Creasing and sagging of the skin, described in Chapter 15, extends into old age. In addition, oil glands that lubricate the skin become less active, leading to dryness and roughness. "Age spots" increase; in some individuals, the arms, backs of the hands, and face may be dotted with these pigmented marks. Blood vessels can be seen beneath the more transparent skin, which has largely lost its layer of fatty support (Robert, Labat-Robert, & Robert, 2009). This further limits ability to adapt to hot and cold temperatures. The face is especially likely to show these effects, as it is frequently exposed to the sun, which accelerates aging. Other factors that contribute to facial wrinkling and age spots include long-term alcohol use, cigarette smoking, and psychological stress. Additional facial changes occur: The nose and ears broaden as new cells are deposited on the outer layer of the skeleton. And especially in older adults with a history of poor dental care, teeth may be yellowed, cracked, and chipped, and gums may have receded (Whitbourne, 2002). As hair follicles under the skin's surface die, hair on the head thins in both sexes, and the scalp may be visible. Body build changes as well. Height continues to decline, especially in women, as loss of bone mineral content leads to further collapse of the spinal column. Weight generally drops after age 60 because of additional loss of lean body mass (bone density and muscle), which is heavier than the fat deposits accumulating on the torso. Several factors affect mobility. The first is muscle strength, which generally declines at a faster rate in late adulthood than in middle age (Reid & Fielding, 2012). Second, bone strength deteriorates because of reduced bone mass. Third, strength and flexibility of the joints and the ligaments and tendons (which connect muscle to bone) diminish. In her eighties, Ruth's reduced ability to support her body, flex her limbs, and rotate her hips made walking at a steady, moderate pace, climbing stairs, and rising from a chair difficult. In Chapter 13, we noted that endurance athletes who continue training retain their muscular physiques and much of their strength into their sixties and seventies (Sandri et al., 2014). Among nonathletes as well, a history of regular leisure time physical activity translates into greater mobility in late life (McGregor, Cameron-Smith, & Poppitt, 2014). At the same time, a carefully planned exercise program for older adults can enhance joint flexibility and range of movement.

Memory in late adulthood

In late adulthood, difficulties with episodic memory—retrieval of everyday experiences—rise substantially. In comparison, semantic memory—general knowledge removed from the context in which it was first learned—is better preserved.

Cardiovascular and Respiratory Systems in late adulthood

In late adulthood, signs of change in the cardiovascular and respiratory systems become more apparent. In their sixties, Ruth and Walt noticed that they felt more physically stressed after running to catch a bus or to cross a street before the light changed. As the years pass, the heart muscle becomes more rigid, and some of its cells die while others enlarge, leading the walls of the left ventricle (the largest heart chamber, from which blood is pumped to the body) to thicken. In addition, artery walls stiffen and accumulate some plaque (cholesterol and fats) due to normal aging (much more in those with atherosclerosis). Finally, the heart muscle becomes less responsive to signals from pacemaker cells within the heart, which initiate each contraction (Larsen, 2009). As a combined result of these changes, the heart pumps with less force, maximum heart rate decreases, and blood flow throughout the circulatory system slows. This means that sufficient oxygen may not be delivered to body tissues during high physical activity. Changes in the respiratory system compound the effects of reduced oxygenation. Because lung tissue gradually loses its elasticity, vital capacity (amount of air that can be forced in and out of the lungs) is reduced by half between ages 25 and 80. As a result, the lungs fill and empty less efficiently, causing the blood to absorb less oxygen and give off less carbon dioxide (Galetta et al., 2012). This explains why older people increase their breathing rate more and feel more out of breath while exercising—deficiencies that are more extreme in lifelong smokers and in people who are overweight or who have had many years of exposure to environmental pollutants.

Vascular Dementia

In vascular dementia, a series of strokes leaves areas of dead brain cells, producing step-by-step degeneration of mental ability, with each step occurring abruptly after a stroke. Approximately 15 percent of all dementia cases in Western nations are vascular. The disorder affects 1.5 percent of Americans over age 65 (Sullivan & Elias, 2016). At the same time, many victims of Alzheimer's disease also show vascular damage. Heredity indirectly affects cerebrovascular dementia through high blood pressure, cardiovascular disease, and diabetes, each of which increases the risk of stroke. And environmental factors—including cigarette smoking, heavy alcohol use, high salt intake, very low dietary protein, obesity, inactivity, and psychological stress—also heighten stroke risk (Sahathevan, Brodtmann, & Donnan, 2011). Because of their greater susceptibility to cardiovascular disease, more men than women have vascular dementia. The disease also varies among countries. For example, the occurrence of vascular dementia is particularly high in Japan (Ikejima et al., 2014). Although a low-fat diet reduces Japanese adults' risk of cardiovascular disease, high intake of alcohol and salt and a diet low in animal protein increase the risk of stroke. Although Japan presents a unique, contradictory picture (there, cardiovascular disease is low, and stroke is high), in most cases vascular dementia is caused by atherosclerosis. The U.S. incidence of vascular dementia has dropped in the last two decades, largely as a result of the decline in heart disease and more effective stroke prevention methods (U.S. Department of Health and Human Services, 2015d).

What Can We Learn About Aging from Centenarians?

Jeanne Louise Calment, listed in Guinness World Records as the longest-lived person whose age could be documented, was born in Arles, France, in 1875 and died there in 1997, at age 122. Heredity undoubtedly contributed to her longevity: Her father lived to age 94, her mother to 86. As a young woman, she was healthy and energetic; she bicycled, swam, roller-skated, and played tennis. Jeanne's friends attributed her longevity to an agreeable disposition and resistance to stress. "If you can't do anything about it," she once said, "don't worry about it." Jeanne took up fencing at age 85 and rode a bicycle until 100. Shortly thereafter, she moved into assisted living (see page 478), where she blossomed, becoming a celebrity because of both her age and her charming personality. Alert and quick-witted until her final year, she recommended laughter as the best recipe for long life. The past 25 years have seen a nearly fivefold increase in the world's centenarian population, with women outnumbering men by 5 to 1. Currently, U.S. centenarians, though still rare (a fraction of 1 percent of the population), number about 72,000 (Stepler, 2016). In a study of 96 U.S. centenarians, one-fourth reached age 100 with no major chronic disease, nearly as many had no physical disabilities, and 55 percent were free of cognitive impairments (Alishaire, Beltrán-Sánchez, & Crimmins, 2015). They were generally healthier than a comparison group of very old adults who died before their hundredth birthday. These robust centenarians—leading active, autonomous lives—are of special interest because they represent the ultimate potential of the human species. Results of several longitudinal studies reveal that they are diverse in years of education (none to postgraduate), economic well-being (very poor to very rich), and ethnicity. At the same time, their physical condition and life stories reveal common threads. Health Centenarians usually have grandparents, parents, and siblings who reached very old age, indicating a genetically based survival advantage (Cosentino et al., 2013; Perls et al., 2002). Some centenarians share with siblings a segment of identical DNA on the fourth chromosome, suggesting that a certain gene, or several genes, may increase the likelihood of exceptionally long life (Perls & Terry, 2003). Robust centenarians have a low incidence of genes associated with immune-deficiency disorders, cancer, and Alzheimer's disease. Consistent with these findings, they usually have efficiently functioning immune systems, and after-death examinations reveal few brain abnormalities (Silver & Perls, 2000). Other robust centenarians function well despite underlying chronic disease—typically atherosclerosis, other cardiovascular problems, and brain pathology (Berzlanovich et al., 2005; Evert et al., 2003). As a group, robust centenarians are of average or slender build and practice moderation in eating. Many have most or all of their own teeth—another sign of unusual physical health. The large majority have never smoked, and most report lifelong physical activity extending past age 100 (Hagberg & Samuelson, 2008; Kropf & Pughv, 1995). Personality In personality, these very senior citizens appear highly optimistic (Jopp & Rott, 2006). In a study in which robust centenarians retook personality tests after 18 months, they reported more fatigue and depression, perhaps in response to increased frailty at the very end of their lives. But they also scored higher in tough-mindedness, independence, emotional security, and openness to experience—traits that may be vital for surviving beyond 100 (Martin, Long, & Poon, 2002). An important contributor to their favorable mental health and longevity is social support, especially close family bonds and a long and happy marriage (Margrett et al., 2011). An unusually large percentage of centenarian men—about one-fourth—are still married. Activities Robust centenarians have a history of community involvement—working for just causes that are central to their growth and happiness. Their past and current activities often include stimulating work, leisure pursuits, and learning, which may help sustain their good cognition and life satisfaction (Antonini et al., 2008; Weiss-Numeroff, 2013). Writing letters, poems, plays, and memoirs; making speeches; teaching music lessons and Sunday school; nursing the sick; chopping wood; selling merchandise, bonds, and insurance; painting; practicing medicine; and preaching sermons are among robust centenarians' varied involvements. In several cases, illiterate centenarians learned to read and write. In sum, robust centenarians illustrate typical development at its best. These independent, mentally alert, happy 100-year-olds reveal how a healthy lifestyle, personal resourcefulness, and close ties to family and community can build on biological strengths, thereby pushing the limits of an active, fulfilling life.

Overcoming Stereotypes of Aging

Many older adults report experiences of prejudice and discrimination (Perdue, 2016). These include being ignored, talked down to, or assumed to be unable to hear or understand, and exposure to disparaging jokes about older people. Like gender stereotypes, aging stereotypes often operate automatically, without awareness; people "see" older adults in stereotypical ways, even when they appear otherwise (Kite et al., 2005). As older people encounter negative messages about aging, they experience stereotype threat, which results in diminished performance on tasks related to the stereotype (see page 255 in Chapter 9). In a growing number of studies, aging adults were exposed to words associated with either negative aging stereotypes ("decrepit," "confused") or positive aging stereotypes ("sage," "enlightened"). Those in negative-stereotype conditions displayed a more intense physiological response to stress, greater help-seeking and feelings of loneliness, and worse self-efficacy, physical performance, recall memory, and appraisals of their own health and memory capacity (Bouazzaoui et al., 2015; Coudin & Alexopoulos, 2010; Levy et al., 2012; Mazerolle et al., 2015). Positive stereotypes, in contrast, reduce stress and foster physical and mental competence (Bolkan & Hooker, 2012). In another longitudinal investigation, people with positive self-perceptions of aging—who, for example, agreed with such statements as "As I get older, things are better than I thought they'd be"—lived, on average, 7½ years longer than those with negative self-perceptions. This survival advantage remained after gender, SES, loneliness, and physical health status were controlled (Levy et al., 2002). Adults with less education are especially susceptible to the detrimental effects of aging stereotypes, perhaps because they tend to accept those messages uncritically (Andreoletti & Lachman, 2004). In cultures where older adults are treated with deference and respect, aging can be a source of pride. In the native language of the Inuit people of Canada, the closest word to "elder" is isumataq, or "one who knows things"—a high status that begins when a couple becomes head of the extended family unit. When Inuit older adults were asked for their thoughts on aging well, they mentioned attitudes—a positive approach to life, interest in transmitting cultural knowledge to young people, and community involvement—nearly twice as often as physical health (Collings, 2001). Despite inevitable declines, physical aging can be viewed with either optimism or pessimism. As Walt commented, "You can think of your glass as half full or half empty."

Interventions for Caregivers of Older Adults with Dementia

Margaret, wife and caregiver of a 71-year-old Alzheimer's patient, sent a desperate plea to an advice columnist at her local newspaper: "My husband can't feed or bathe himself, or speak to anyone or ask for assistance. I must constantly anticipate his needs and try to meet them. Please help me. I'm at the end of my rope." The effects of Alzheimer's disease are devastating not just to victims but also to family members who provide care with little or no outside assistance. Caregiving under these conditions has been called the "36-hour day." Although the majority of family caregivers are middle-aged, an estimated one-third are older adults caring for a spouse or an aging parent. Many are in poor health themselves, yet the number of hours dedicated to caregiving increases with caregiver age and is especially high among ethnic minority older adults, whose cultures emphasize care as a family obligation (Alzheimer's Association, 2016a). Severity of cognitive impairments and behavior problems in care recipients are strong predictors of weakening caregiver physical and mental health (AARP, 2015). The close relationship between the caregiver and the suffering individual—involving shared memories, experiences, and emotions—seems to heighten caregiver risk (Monin & Schulz, 2009). Most communities offer interventions designed to support family caregivers, but they need to be expanded and made more cost-effective. Those that work best address multiple needs: knowledge, coping strategies, caregiving skills, and respite. Knowledge Virtually all interventions try to enhance knowledge about the disease, caregiving challenges, and available community resources. Knowledge is usually delivered through classes, but websites with wide-ranging information on caregiving, and online communication technologies through which caregivers can obtain and share information, also exist (Czaja, 2016). Gains in knowledge, however, must be combined with other approaches to improve caregivers' well-being. Coping Strategies Many interventions teach caregivers everyday problem-solving strategies for managing the dependent person's behavior, along with techniques for dealing with their own negative thoughts and feelings, such as resentment about having to provide constant care. Modes of delivery include support groups, individual therapy, and classes providing coaching in effective coping strategies (Roche, MacCann, & Croot, 2016). All yield improvements in caregivers' adjustment and in patients' disturbing behaviors, both immediately and in follow-ups more than a year later. Caregiving Skills Caregivers benefit from lessons in how to communicate with older adults who can no longer express thoughts and emotions clearly. Helpful techniques include sustaining good eye contact to convey interest and caring; speaking slowly, with short, simple words; using gestures to reinforce meaning; waiting patiently for a response; refraining from interrupting, correcting, or criticizing; and introducing pleasant activities, such as music and slow-paced children's TV programs, that relieve agitation (Alzheimer's Association, 2016b). Interventions that teach communication skills through active practice reduce patients' troublesome behavior and, as a result, lessen caregivers' distress and boost their sense of self-efficacy (Eggenberger, Heimerl, & Bennett, 2013; Irvine, Ary, & Bourgeois, 2003). Respite Caregivers usually say that respite—time away from providing care—is the assistance they most desire. But they may be reluctant to accept friends' and relatives' informal offers to help because of guilt. And they may not use formal services (such as adult day care or temporary placement in a care facility) because of cost or worries about the older adult's adjustment. Yet respite at least twice a week for several hours improves physical and mental health by enabling caregivers to sustain a balanced life (Lund et al., 2010b). For respite time to be most effective, planning how best to use it is crucial. Caregivers who end up spending respite hours doing housework, shopping, or working usually remain dissatisfied (Lund et al., 2009). Those who engage in activities they had wanted and planned to do gain in psychological well-being. Intervention Programs Multifaceted intervention programs that are tailored to caregivers' individual needs make a substantial difference in their lives. Such interventions usually delay institutional placement of dementia patients as well. In the Resources for Enhancing Alzheimer's Caregiver Health (REACH) initiative, an array of "active" intervention programs, each including some or all of the ingredients just described, were evaluated against "passive" interventions providing only information and referral to community agencies. Among more than 1,200 participating caregivers, those receiving six months of active intervention declined more in self-reported burden. And one program providing family therapy in the home—through a telephone system facilitating frequent communication among therapist, caregiver, family members, and other support systems—substantially reduced caregiver depressive symptoms (Gitlin et al., 2003; Schultz et al., 2003). In additional evaluations, REACH intervention programs enhanced physical and mental health among caregivers of diverse ethnicities—African American, European American, and Hispanic (Basu, Hochhalter, & Stevens, 2015; Belle et al., 2006; Elliott, Burgio, & DeCoster, 2010).

Mental Disabilities

Normal age-related cell death in the brain, described earlier, does not lead to loss of ability to engage in everyday activities. But when cell death and structural and chemical abnormalities are profound, serious deterioration of mental and motor functions occurs. Dementia refers to a set of disorders occurring almost entirely in old age in which many aspects of thought and behavior are so impaired that everyday activities are disrupted. Dementia strikes 13 percent of adults over age 65. Approximately 2 to 3 percent of people ages 65 to 69 are affected; the rate doubles every 5 to 6 years until it reaches about 22 percent among those ages 85 to 89 and over half after age 90—trends that apply to the United States and other Western nations (Prince et al., 2013). Beyond age 80, a larger proportion of women than men have dementia, perhaps reflecting the biological sturdiness of the oldest men. Although dementia rates are similar across most ethnic groups, older African Americans have about twice the incidence, and Hispanics about one and one-half times the incidence, as whites (Alzheimer's Association, 2016a). Associated risk factors, not race, are responsible, as we will see shortly. About a dozen types of dementia have been identified. Some are reversible with proper treatment, but most are irreversible and incurable. A few forms, such as Parkinson's disease,1 involve deterioration in subcortical brain regions (primitive structures below the cortex) that often extends to the cerebral cortex and, in many instances, results in brain abnormalities resembling Alzheimer's disease (Goedert, 2015). But in the majority of dementia cases, subcortical brain regions are intact, and progressive damage occurs only to the cerebral cortex. The two most common forms of cortical dementia are Alzheimer's disease and vascular dementia.

Motor Vehicle Accidents

Older adults have higher rates of traffic violations, accidents, and fatalities per mile driven than any other age group, with the exception of drivers under age 25 (Heron, 2015). The high rate of injury persists, even though many older people, especially women, limit their driving after noticing that their ability to drive safely is slipping. The greater older adults' visual processing difficulties, the higher their rate of moving violations and crashes (Friedman et al., 2013). Compared with young drivers, older people are less likely to drive quickly and recklessly but more likely to fail to heed signs, yield the right of way, and turn appropriately. They often try to compensate for their difficulties by being more cautious. Slowed reaction time and indecisiveness pose hazards, too. In Chapter 15, we noted that executive function declines with age: Tasks requiring spatial working memory, inhibition of irrelevant information and impulses, and flexible shifting of attention between activities become increasingly challenging (see page 428). Because these skills are essential for safe driving, aging adults are at high risk for collisions at busy intersections and in other complex traffic situations. Nevertheless, older people usually try to drive as long as possible. Giving up driving results in loss of personal control over daily life and decline in productive roles, such as paid work and volunteering (Curl et al., 2014). Specially trained driver rehabilitation consultants—affiliated with hospitals, drivers licensing agencies, or U.S. Area Agencies on Aging (see pages 51-52 in Chapter 2)—can help assess older adults' capacity to continue driving or counsel them to use other transportation options.

Effective Coping Strategies

Older people who report a high sense of personal control usually deal with physical changes through problem-centered coping strategies. One 75-year-old who lost sight in one eye consulted an occupational therapist for advice and, to compensate for reduced depth perception and visual field, trained himself to use more side-to-side head movements. In contrast, older adults who consider age-related declines inevitable and uncontrollable tend to be passive when faced with them, to report more physical and mental health difficulties, and to experience steeper late-life declines in health (Gerstorf et al., 2014; Lachman, Neupert, & Agrigoroaei, 2011; Ward, 2013). Sense of control varies across cultures: We have seen that the United States is less generous than other industrialized nations in government-supported health care and social security benefits (see pages 51-52 in Chapter 2). In one study, sense of personal control was a stronger predictor of older adults' health status in the United States than it was in England, where government policies do more to support good health throughout the lifespan (Clarke & Smith, 2011). When physical disabilities become severe, sense of control has diminishing returns, no longer having as much impact on health status. Aging adults with substantial physical impairments cope more effectively when they acknowledge reduced control and accept the need for caregiver or equipment assistance (Clarke & Smith, 2011; Slagsvold & Sørensen, 2013). But doing so may be more difficult for many older Americans, who are accustomed to a "culture of personal control," than for older people elsewhere in the world.

Falls

One day, Ruth fell down the basement steps and lay there with a broken ankle until Walt arrived home an hour later. Ruth's tumble represents the leading type of accident in late life. About one-third of adults over age 65 and half of those over age 80 have experienced a fall within the past year (Centers for Disease Control and Prevention, 2016c). Declines in vision, hearing, mobility, muscle strength, and cognitive functioning; depressed mood; use of medications that affect mental processing; and development of certain chronic illnesses (such as arthritis) increase the risk of falling (Rubenstein, Stevens, & Scott, 2008). Serious injury results about 20 percent of the time, most commonly hip fracture. It increases fifteenfold from ages 65 to 85 and frequently leads to serious health complications. One in five older hip fracture patients dies within a year of the injury (Centers for Disease Control and Prevention, 2015f). Of those who survive, half never regain the ability to walk without assistance. Falling can also impair health indirectly, by promoting fear of falling. Nearly half of older adults who have fallen admit that they purposefully avoid activities because they are afraid of falling again. In this way, a fall can limit mobility and social contact (Painter et al., 2012). Although an active lifestyle may expose older people to more situations that can cause a fall, the health benefits of activity far outweigh the risk of serious injury due to falling.

Physical Changes in late adulthood

Physical declines become more apparent in late adulthood as more organs and systems of the body are affected by biological aging. The majority of people ages 65 and older are capable of living active, independent lives, but with age, growing numbers need assistance. After age 75, about 9 percent of Americans have difficulty carrying out activities of daily living (ADLs)—basic self-care tasks required to live on one's own, such as bathing, dressing, getting in and out of bed or a chair, or eating. And about 17 percent cannot carry out instrumental activities of daily living (IADLs)—tasks necessary to conduct the business of daily life and also requiring some cognitive competence, such as telephoning, shopping, food preparation, housekeeping, and paying bills. The proportion of older adults with these limitations rises sharply with age (U.S. Department of Health and Human Services, 2015d). Nevertheless, most body structures can last into our eighties and beyond, if we take good care of them. For an overview of the physical changes we are about to discuss, return to Table 13.1 on page 359.

Problem Solving in late adulthood

Problem solving is another cognitive skill that illustrates how aging brings not only declines but also adaptive changes. Problem solving in the laboratory declines in late adulthood (Finucane et al., 2005). Older adults' memory limitations make it hard to keep all relevant facts in mind when dealing with a complex hypothetical problem. For similar reasons, financial decision making—evaluating loan and investment options—tends to be less effective than it was in midlife (see page 430 in Chapter 15). Yet the everyday problems older adults encounter differ from hypothetical problems devised by researchers—and also from everyday problems experienced at earlier ages. After retirement, older adults do not have to deal with workplace problems. Their children are typically grown and living on their own, and their marriages have endured long enough to have fewer difficulties. With age, major concerns involve dealing with extended-family relationships (for example, expectations of adult children that they babysit grandchildren) and managing IADLs, such as preparing nutritious meals, paying bills, and attending to health concerns. Older people are active and effective in solving problems of everyday life, as long as they perceive those problems as under their control and important (Berg & Strough, 2011). They generate a smaller number of strategies compared to young and middle-aged adults, perhaps because they know which ones are most likely to be helpful due to their long life experience (Strough et al., 2008). At the same time, older adults are particularly good at adapting strategies to fit problem conditions—home, relatives, and friends (Skinner, Berg, & Uchino, 2014). And because they are especially concerned with maintaining positive relationships, as we will see in Chapter 18, they usually do what they can to avoid interpersonal conflicts. The health arena illustrates the adaptiveness of everyday problem solving in late life. Older adults make faster decisions about whether they are ill, seek medical care sooner, and select treatments more quickly than young and middle-aged adults (Meyer, Russo, & Talbot, 1995). This swift response of older people is interesting in view of their slower cognitive processing. Research reveals that they have accumulated more health-related knowledge, which enables them to move ahead with greater certainty (Meyer, Talbot, & Ranalli, 2007). Acting decisively when faced with health risks is sensible in old age. Finally, older adults report that they often consult others—generally spouses and adult children, but also friends, neighbors, and members of their religious congregation—for advice about everyday problems (Strough et al., 2003). And compared with younger married couples, older couples more often collaborate in problem solving, and researchers judge their jointly generated strategies as highly effective—even on demanding tasks that require complex memory and reasoning (Peter-Wight & Martin, 2011; Rauers et al., 2011). In jointly solving problems, older people seem to compensate for moments of cognitive difficulty.

Increasing the Effectiveness of Educational Experiences for Older Adults

Provide a positive learning environment: Many older adults have internalized negative stereotypes of their own abilities and come to the learning environment with low self-efficacy. A supportive group atmosphere helps convince them that they can learn. Allow ample time to learn new information: Rate of learning varies widely among older adults. Presenting information over multiple sessions or allowing for self-paced instruction aids mastery. Present information in a well-organized fashion: Older adults do not organize information as effectively as younger adults. Material that is outlined, presented, and then summarized enhances memory and understanding. Digressions make a presentation harder to comprehend. Relate information to older adults' knowledge and experiences: Relating new material to what older adults have already learned, by drawing on their extensive knowledge and experiences and giving many vivid examples, enhances recall. Adapt the learning environment to fit changes in sensory systems: Adequate lighting, availability of large-print reading materials, appropriate sound amplification, reduced background noise, and clear, well-organized visual aids ease information processing.

Cognitive Development in late adulthood

Ruth's complaints to her doctor about difficulties with memory and verbal expression reflect common concerns about cognitive functioning in late adulthood. Decline in speed of processing, under way throughout the adult years, is believed to affect many aspects of cognition in old age. In Chapter 15, we noted that reduced efficiency of thinking contributes to (but may not fully explain) decrements in executive function, especially working-memory capacity and working-memory updating. Declines in inhibition of irrelevant information and impulses, in flexibly shifting between tasks and mental operations, in use of memory strategies, and in retrieval from long-term memory continue in the final decades of life, affecting many aspects of cognitive aging. Return to Figure 15.5 on page 427, and note that the more a mental ability depends on fluid intelligence (biologically based information-processing skills), the earlier it starts to decline. In contrast, mental abilities that rely on crystallized intelligence (culturally based knowledge) are sustained longer. But maintenance of crystallized intelligence depends on continued opportunities to use and enhance cognitive skills. When these are available, crystallized abilities—vocabulary, general information, and expertise in specific endeavors—can offset losses in fluid intelligence. Look again at Figure 15.5. In advanced old age, decrements in fluid intelligence limit what people can accomplish even with cultural supports, including a rich background of experience, knowledge of how to remember and solve problems, and a stimulating daily life. Consequently, crystallized intelligence shows a modest decline. Generally, loss outweighs improvement and maintenance as people approach the end of life, but plasticity is still possible: Some individuals display high maintenance and minimal loss at very old ages (Baltes & Smith, 2003; Schaie, 2013). Research reveals greater individual variation in cognitive functioning in late adulthood than at any other time of life (Riediger, Li, & Lindenberger, 2006). Besides fuller expression of genetic and lifestyle influences, increased freedom to pursue self-chosen courses of action—some that enhance and others that undermine cognitive skills—may be responsible. How can older adults make the most of their cognitive resources? According to one view, those who sustain high levels of functioning engage in selective optimization with compensation: Narrowing their goals, they select personally valued activities to optimize (or maximize) returns from their diminishing energy. They also find new ways to compensate for losses (Baltes, Lindenberger, & Staudinger, 2006; Napolitano & Freund, 2016). For example, when famed pianist Arthur Rubinstein was asked at age 80 how he managed to sustain such extraordinary playing, he replied that he was selective; he played fewer pieces, carefully choosing those within range of his current skill and stamina. This enabled him to optimize his energy; he could practice each piece more. He also devised compensatory techniques for a decline in playing speed. For example, before a fast passage, he played extra slowly, so the fast section appeared to his audience to move more quickly. In late adulthood, personal goals—while still including gains—increasingly focus on maintaining abilities and preventing losses (Ebner, Freund, & Baltes, 2006). As we review major changes in memory, language processing, and problem solving, we will consider ways that older adults optimize and compensate in the face of declines. We will also see that certain abilities that depend on extensive life experience, not processing efficiency, are sustained or increase in old age.

Prospective Memory

So far, we have considered various aspects of retrospective memory (remembrance of things past). Prospective memory refers to remembering to engage in planned actions in the future. The amount of mental effort required determines whether older adults have trouble with prospective memory. For example, remembering a dinner date set for an unusual time (Tuesday at 7:15 p.m.) is more challenging than remembering one regularly scheduled for the same time (every Thursday at 6 p.m.). In the laboratory, older adults do better on event-based than on time-based prospective memory tasks. In an event-based task, an event (such as a certain word appearing on a computer screen) serves as a cue for remembering to do something (pressing a key) while the participant engages in an ongoing activity (reading paragraphs) (Kliegel, Jäger, & Phillips, 2008). In time-based tasks, the adult must engage in an action after a certain time interval has elapsed, without any obvious external cue (for example, pressing a key every 10 minutes). Time-based prospective memory requires considerable initiative to keep the planned action in mind and monitor the passage of time while also performing an ongoing activity (Einstein, McDaniel, & Scullin, 2012). Consequently, declines in late adulthood are considerable. But difficulties with prospective memory seen in the laboratory do not appear in real life, where adults are highly motivated to remember and good at setting up event-based reminders for themselves, such as a buzzer ringing in the kitchen or a note tacked up prominently (Schnitzspahn et al., 2011, 2016). In this way, older adults compensate for their reduced-capacity working memories and the challenge of dividing attention between what they are doing now and what they must do in the future. Nevertheless, once a prospective memory task is finished, older adults find it harder than younger adults to deactivate, or inhibit, their intention to engage in the future action. Hence, they sometimes repeat the task again (Scullin et al., 2011). Whereas forgetting whether one has washed one's hair and doing so a second time is harmless, repeating a dose of medication can be dangerous. Older adults benefit from a system of reminders that regularly scheduled tasks have been completed, and they often arrange such systems themselves.

Lifelong Learning

The competencies aging adults need to live in our complex, changing world are the same ones younger people need: communicating effectively through spoken and written systems; locating information, sorting through it, and selecting what is needed; using math strategies, such as estimation; planning and organizing activities, including making good use of time and resources; mastering new technologies; and understanding past and current events and the relevance of each to their own lives. Older people also need to acquire new, problem-centered coping strategies—ways to sustain health and operate their households efficiently and safely—and updated vocational skills, for those who continue to work. Participation of older adults in continuing education has increased substantially over the past few decades. In its most recently reported year, Road Scholar campus-based programs, and their recent extension to travel experiences around the world, attracted more than 100,000 American and Canadian older adults. Some programs make use of community resources through classes on local ecology or folk life. Others focus on innovative topics and experiences—writing one's own life story, discussing contemporary films with screenwriters, whitewater rafting, Chinese painting and calligraphy, or acquiring French language skills. Travel programs are enriched by in-depth lectures and expert-led field trips. Similar educational programs have sprung up in the United States and elsewhere. The Bernard Osher Foundation collaborates with more than 120 U.S. universities to establish Osher Lifelong Learning Institutes on campuses. Each offers older adults a wide array of stimulating learning experiences, from auditing regular courses, to forming learning communities that address common interests, to helping to solve community problems. Participants in the programs just mentioned tend to be active, well-educated, and financially well-off. Much less is available for older people with little education and limited income. Community senior centers with inexpensive offerings related to everyday living attract more low-SES people (Formosa, 2014). Regardless of course content and which older adults attend, using the techniques summarized in Applying What We Know above increases the effectiveness of educational experiences. Older participants in continuing education report a rich array of benefits—understanding new ideas in many disciplines, learning new skills that enrich their lives, making new friends, and developing a broader perspective on the world (Preece & Findsen, 2007). Furthermore, participants come to see themselves differently. Many abandon their own ingrained negative stereotypes of aging when they realize that adults in late life—including themselves—can still engage in complex learning. Older adults' willingness to acquire new knowledge and skills is apparent in the recent, rapid rise in their use of online technology as they discover its many practical benefits, including assistance with shopping, banking, health-care management, and communication. Currently, about 60 percent of adults ages 65 and older access the Internet, with the majority going online daily. As noted on page 451 in Chapter 16, 35 percent of aging adults are users of social media sites, primarily Facebook (Charness & Boot, 2016; Perrin, 2015). Still, older people have joined the computer and Internet community to a lesser extent than younger people. But with patient training, support, and modified equipment and software to suit their physical and cognitive needs, older adults become devoted and skilled users. The educational needs of aging adults are likely to be given greater attention in coming decades, as their numbers grow and they assert their right to lifelong learning. Once this happens, false stereotypes—"they are too old to learn" or "education is for the young"—are likely to weaken and, perhaps, disappear.

Associative Memory

The memory difficulties just described are part of a general, age-related decline in binding information into complex memories (Smyth & Naveh-Benjamin, 2016). Researchers call this an associative memory deficit, or difficulty creating and retrieving links between pieces of information—for example, two items or an item and its context, such as Ruth's attempt to remember the name of the movie with the child actor or where she had seen the movie. To find out whether older adults have greater difficulty with associative memory than younger adults, researchers show them pairs of unrelated words or pictures of objects (such as table-overcoat or sandwich-radio) and ask that they study the pairs for an upcoming memory test. During the test, one group of participants is given single items, some that had appeared in the study phase and some that had not, and asked to indicate the ones they had studied. The other group is given item pairs, some intact from the study phase (table-overcoat) and some rearranged (overcoat-radio), and asked to indicate which pairs they had studied. Older adults do almost as well as younger adults on single-item memory tests (Guez & Lev, 2016; Old & Naveh-Benjamin, 2008; Ratcliff & McKoon, 2015). But they perform far worse on item-pair tests. Older people have great difficulty remembering widely varying associations, including face-name, face-face, word-voice, and person-action pairings. Easing task demands by providing older adults with helpful memory cues improves their associative memory. For example, to associate names with faces, older people profit from mention of relevant facts about those individuals. And when older adults are directed to use the memory strategy of elaboration (relating word pairs by generating a verbal statement or mental image of their relationship), the young-old difference in memory is greatly reduced (Bastin et al., 2013; Naveh-Benjamin, Brav, & Levy, 2007). Clearly, associative deficits are substantially affected by lack of strategy use that helps bind information into integrated wholes.

Nutrition and Exercise in late adulthood

The physical changes of late life lead to an increased need for certain nutrients—calcium and vitamin D to protect the bones; zinc and vitamins B6, C, and E to protect the immune system; and vitamins A, C, and E to protect against excess free radicals. Yet declines in physical activity, in the senses of taste and smell, and in ease of chewing (because of deteriorating teeth) can reduce the quantity and quality of food eaten. Furthermore, the aging digestive system has greater difficulty absorbing certain nutrients, such as protein, calcium, and vitamin D. And older adults who live alone may have problems shopping or cooking and may feel less like eating by themselves. Together, these physical and environmental conditions increase the risk of dietary deficiencies. In addition to a healthy diet, exercise continues to be a powerful health intervention. Sedentary healthy older adults up to age 80 who begin endurance training (walking, cycling, aerobic dance) show gains in vital capacity that compare favorably with those of much younger individuals. And weight-bearing exercise begun in late adulthood—even as late as age 90—promotes muscle size and strength (deJong & Franklin, 2004; Pyka et al., 1994). This translates into improved walking speed, balance, posture, and ability to carry out everyday activities. Exercise also increases blood circulation to the brain, which helps preserve brain structures and behavioral capacities. Brain scans show that physically fit older people experience less tissue loss in the cerebral cortex (Erickson et al., 2010; Miller et al., 2012). And compared with physically inactive agemates, previously sedentary older adults who initiated a program of regular, moderate to vigorous exercise displayed gains in size of diverse cortical areas, including the prefrontal cortex and hippocampus, with benefits for executive function and memory (Erickson, Leckie, & Weinstein, 2014). These findings offer clear biological evidence for the role of late-life physical activity in preserving central nervous system health. Older people who come to value the intrinsic benefits of physical activity—feeling stronger, healthier, and more energetic—are likely to engage in it. Yet about 60 percent of U.S. 65- to 74-year-olds and 75 percent of those over age 75 do not exercise regularly (U.S. Department of Health and Human Services, 2015d).

Touch in late adulthood

Touch discrimination is especially crucial for certain adults, such as the severely visually impaired reading Braille and people making fine judgments about texture—for example, in art and handicraft activities. In later life, capacity to discriminate detailed surface properties and identify unfamiliar objects by touch declines. Waning of touch perception on the hands, especially the fingertips—believed to be due to loss of touch receptors in certain regions of the skin and slowing of blood circulation to the extremities—contributes (Stevens & Cruz, 1996). In addition, decrements in fluid abilities, especially spatial orientation, are influential (see pages 426-427 in Chapter 15) (Kalisch et al., 2012). Fluid skills are strongly correlated with older adults' tactile performance. Although touch sensitivity typically diminishes, responsiveness to the emotionally pleasant quality of soft, gentle stroking is an exception: Older adults rate it as more pleasurable than younger people (Sehlstedt et al., 2016). Perhaps fewer touches from others in late life enhance enjoyment of sensitive touching when it happens.

Taste and smell in late adulthood

Walt's brother Dick was a heavy smoker. In his sixties, he poured salt and pepper over his food and asked for "extra hot" in Mexican and Indian restaurants. Dick's reduced sensitivity to the four basic tastes—sweet, salty, sour, and bitter—is evident in more than half of adults after age 60 and up to 80 percent after age 80, largely due to a decline in number and distribution of taste buds on the tongue. Older adults also have greater difficulty recognizing familiar foods by taste alone (Correia et al., 2016; Methven et al., 2012). Cigarette smoking, dentures, medications, and environmental pollutants can affect taste perception. When taste is harder to detect, food is less enjoyable, increasing the likelihood of dietary deficiencies. Besides enhancing food enjoyment, smell has a self-protective function. An aging person who has difficulty detecting rancid food, gas fumes, or smoke may be in a life-threatening situation. A decrease in the number of smell receptors, along with loss of neurons in brain regions involved in processing odors, contributes to declines in odor sensitivity after age 60, with one-fourth of people over age 70 affected (Attems, Walker, & Jellinger, 2015; Correia et al., 2016). Researchers believe that odor perception not only wanes but becomes distorted, a change that may promote complaints that "food no longer smells and tastes right."

Long-Term Health Care

When Ida moved into Ruth's home, Ruth promised never to place Ida in an institution. But as Ida's condition worsened and Ruth faced health problems of her own, she couldn't keep her word. Reluctantly, Ruth placed Ida in a nursing home. Advancing age is strongly associated with use of long-term health-care services, especially nursing homes. Almost half of U.S. nursing home residents are ages 85 and older. Dementia—especially Alzheimer's disease—most often leads to nursing home placement; frailty is another strong predictor (Harris-Kojetin et al., 2016; Kojima, 2016). Overall, only 3 percent of Americans ages 65 and older are institutionalized, less than half the rates in other Western nations, such as Australia, Belgium, the Netherlands, Switzerland, Sweden, and New Zealand, which provide more generous public financing of institutional care (OECD, 2016). Unless nursing home placement follows hospitalization for an acute illness, U.S. Medicare does not cover it. Instead, older adults must pay for it until their resources are exhausted. At that point, Medicaid (health insurance for the poor) takes over. Consequently, the largest users of nursing homes in the United States are people with either very low or high incomes. Middle-income aging adults and their families are more likely to try to protect their savings from being drained by high nursing home costs. Nursing home use also varies across ethnic groups. For example, European Americans are more likely to be institutionalized than African Americans and Hispanics, who often have large, close-knit extended families with a strong sense of caregiving responsibility. Similarly, Asian and Native-American older adults use nursing homes less often than European Americans (Centers for Medicare and Medicaid Services, 2013; Thomeer, Mudrazija, & Angel, 2014). Overall, families provide at least 60 to 80 percent of all long-term care in Australia, Canada, New Zealand, the United States, and Western Europe. To reduce institutionalized care of older adults and its associated high cost, experts advocate alternatives, such as publicly funded in-home help for family caregivers (see Chapter 16, page 449). Another option that has increased dramatically over the past two decades is assisted living—homelike housing arrangements for older adults who require more help than can be provided at home but less than is usually provided in nursing homes. Assisted living is a cost-effective alternative to nursing homes that prevents unnecessary institutionalization. It also can enhance residents' autonomy, social life, community involvement, and life satisfaction—benefits that we will take up in Chapter 18. In Denmark, the combination of a government-sponsored home-helper system and expansion of assisted-living housing resulted in a substantial reduction in the need for nursing home beds (Hastrup, 2007; Rostgaard, 2012). Strengthening caregiving and health-care services in U.S. assisted-living facilities would result in similarly favorable outcomes. When nursing home placement is necessary, steps can be taken to improve its quality. For example, the Netherlands has established separate facilities designed to meet the different needs of patients with mental and physical disabilities. Institutionalized individuals—like aging adults everywhere—desire a sense of personal control, gratifying social relationships, and meaningful and enjoyable daily activities (Alkema, Wilber, & Enguidanos, 2007). As Chapter 18 will reveal, designing nursing homes to meet these needs promotes both physical and psychological well-being.

Alzheimer's Disease

When Ruth took 79-year-old Ida to the ballet, an occasion the two sisters eagerly anticipated each year, she noticed a change in Ida's behavior. Ida, who had forgotten the engagement, reacted angrily when Ruth arrived unannounced at her door. Driving to the theater, which was in a familiar part of town, Ida got lost—all the while insisting that she knew the way perfectly. As the lights dimmed and the music began, Ida talked loudly and dug noisily in her purse. "Shhhhhh," responded a dozen voices from surrounding seats. "It's just the music!" Ida snapped at full volume. "You can talk all you want until the dancing starts." Ruth was astonished and embarrassed at the behavior of her once socially sensitive sister. Six months later, Ida was diagnosed with Alzheimer's disease, the most common form of dementia, in which structural and chemical brain deterioration is associated with gradual loss of many aspects of thought and behavior. Alzheimer's accounts for an estimated 70 percent of all dementia cases. Approximately 11 percent of Americans over age 65—about 5.2 million people—have the disorder. Of those over age 85, about one-third are affected. In 2030, when all baby boomers will have reached late adulthood, the number of Americans with Alzheimer's is expected to rise to 7.7 million—an increase of more than 50 percent (Alzheimer's Association, 2016a). Symptoms and Course of the Disease The earliest symptoms are often progressively worsening memory problems—forgetting names, dates, appointments, familiar routes of travel, or the need to turn off the kitchen stove. At first, recent memory is most impaired (Bilgel et al., 2014). But as serious disorientation sets in, recall of distant events and such basic facts as time, date, and place evaporates. Faulty judgment puts the person in danger. For example, Ida insisted on driving after she was no longer competent to do so. Personality changes occur—loss of spontaneity and sparkle, anxiety in response to uncertainties created by mental problems, aggressive outbursts, reduced initiative, and social withdrawal. Depression often appears in the early phase of Alzheimer's and other forms of dementia and seems to be part of the disease process (Serra et al., 2010). However, depression may worsen as the older adult reacts to disturbing mental changes. As the disease progresses, skilled and purposeful movements disintegrate. When Ruth took Ida into her home, she had to help her dress, bathe, eat, brush her teeth, and (eventually) walk and use the bathroom. Ida's sleep was disrupted by delusions and imaginary fears. She often awoke in the night and banged on the wall, insisting that it was dinnertime, or cried out that someone was choking her. Over time, Ida lost the ability to comprehend and produce speech. And when her brain ceased to process information, she could no longer recognize objects and familiar people. In the final months, Ida became increasingly immobile, vulnerable to infections, lapsed into a coma, and died. The course of Alzheimer's varies greatly, from a year to as long as 20 years, with those diagnosed in their sixties and early seventies typically surviving longer than those diagnosed at later ages (Brodaty, Seeher, & Gibson, 2012). The average life expectancy for a 70-year-old man with the disease is about 4½ years, for a 70-year-old woman about 8 years. Brain Deterioration A diagnosis of Alzheimer's disease is made through exclusion, after ruling out other causes of dementia by a physical examination and psychological testing—an approach that is more than 90 percent accurate. To confirm Alzheimer's, doctors inspect the brain after death for a set of abnormalities that either cause or result from the disease (Hyman et al., 2012). In the overwhelming majority of cases, however, MRI and PET images of brain volume and activity predict whether individuals will receive an after-death confirmation of Alzheimer's (Vitali et al., 2008). Assessments of the chemical makeup of the blood or cerebrospinal fluid are also strongly predictive (Mattsson et al., 2015; Olsson et al., 2016). Two major structural changes in the cerebral cortex, especially in memory and reasoning areas, are associated with Alzheimer's. Inside neurons, neurofibrillary tangles appear—bundles of twisted threads that are the product of collapsed neural structures and that contain abnormal forms of a protein called tau. Outside neurons, amyloid plaques, dense deposits of a deteriorated protein called amyloid, surrounded by clumps of dead neurons and glial cells, develop. Although some neurofibrillary tangles and amyloid plaques are present in the brains of normal middle-aged and older people and increase with age, they are far more abundant in Alzheimer's victims. Recent findings indicate that a major culprit in the disease is abnormal breakdown of amyloid remaining within neurons, and that plaques reflect the brain's effort to eject harmful amyloid from neurons (National Institute on Aging, 2016). In both Alzheimer's disease and Parkinson's disease, disruptions occur in a key neuronal process responsible for chopping up and disposing of abnormal proteins (Sagare et al., 2013). These damaged proteins (including amyloid) build to toxic levels. Abnormal amyloid causes the generation of signals within neurons and their transfer across synapses to malfunction (Kopeikina et al., 2011). Eventually, damaged amyloid induces heightened, abnormal electrical activity throughout the brain. Abnormal tau in neurofibrillary tangles adds to neuronal breakdown. Tangles disrupt the transport of nutrients and signals from the neuron to its connective fibers. Furthermore, abnormal tau triggers disintegration of nearby normal tau (de Calignon et al., 2012; Liu et al., 2012). Gradually, tau pathology moves across synapses, spreading from neuron to neuron and, over time, from one brain region to the next—thereby amplifying damage. As synapses deteriorate, levels of neurotransmitters decline, neurons die in massive numbers, and brain volume shrinks. Destruction of neurons that release the neurotransmitter acetylcholine, involved in transporting messages between distant brain regions, further disrupts neuronal networks. A drop in serotonin, a neurotransmitter that regulates arousal and mood, may contribute to sleep disturbances, aggressive outbursts, and depression (Rothman & Mattson, 2012). Risk Factors Alzheimer's disease comes in two types: familial, which runs in families, and sporadic, which has no obvious family history. Familial Alzheimer's, responsible for 1 percent or fewer cases, generally has an early onset—between ages 30 and 60—and progresses more rapidly than the later-appearing sporadic type, which typically appears after age 65. Researchers have identified genes on chromosomes 1, 14, and 21, involved in generation of harmful amyloid, that are related to familial Alzheimer's. In each case, the abnormal gene is dominant; if it is present in only one of the pair of genes inherited from parents, the person will develop early-onset Alzheimer's (National Institute on Aging, 2016). Recall that chromosome 21 is involved in Down syndrome. Individuals with this chromosomal disorder who live past age 40 almost always have the brain abnormalities and symptoms of Alzheimer's. Heredity plays a different role in sporadic Alzheimer's, through somatic mutation. About half of people with this form of the disease have an abnormal gene on chromosome 19, which results in excess levels of APOE &4, a blood protein that carries cholesterol throughout the body. Researchers believe that a high blood concentration of APOE &4 affects the expression of a gene involved in regulating insulin. Deficient insulin and resulting glucose buildup in the bloodstream (conditions that, when extreme, lead to diabetes) are linked to brain damage, especially in areas regulating memory, and to high buildup of harmful amyloid in brain tissue (Liu et al., 2013; National Institute on Aging, 2016). In line with these findings, individuals with diabetes have a greatly increased risk of developing Alzheimer's. At present, the abnormal APOE &4 gene is the most widely known risk factor for sporadic Alzheimer's: Those who inherit one APOE &4 allele have a threefold greater risk; those who inherit two alleles have an eight- to twelvefold greater risk (Loy et al., 2014). Genetic testing has also revealed many other genes that seem to make a contribution (National Institute on Aging, 2016). Nevertheless, many sporadic Alzheimer's victims show no known genetic marker, and some individuals with the APOE &4 gene do not develop the disease. Evidence is increasing for the role of a variety of largely modifiable risk factors, including excess dietary fat, physical inactivity, overweight and obesity, smoking, chronic depression, cardiovascular disease, stroke, and (as just noted) diabetes (Baumgart et al., 2015; Institute of Medicine, 2015). Moderate to severe head injuries, possibly by accelerating deterioration of amyloid and tau, also increase Alzheimer's risk, especially among people with the APOE &4 gene (Mckee & Daneshvar, 2015). Individuals subjected to repeated instances, such as boxers, football players, and combat veterans, are especially likely to be affected. The high incidence of Alzheimer's and other forms of dementia among African Americans illustrates the complexity of potential causes. Yoruba village dwellers of Nigeria show a much lower Alzheimer's incidence and a much weaker association between the APOE d4 gene and the disease than African Americans do (Hendrie et al., 2014). Some investigators speculate that intermarriage with European Americans heightened genetic risk among African Americans and that environmental factors translated that risk into reality. Whereas the Yoruba of Nigeria eat a low-fat diet, the African-American diet is high in fat. Eating fatty foods may increase the chances that the APOE d4 gene will lead to Alzheimer's (Hall et al., 2006). The more fat consumed and the higher the blood level of "bad" cholesterol (low-density lipoproteins), the greater the incidence of Alzheimer's. New findings indicate that a substantial number of sporadic Alzheimer's cases are due to epigenetic processes, in which environmental influences modify gene expression (see page 56 in Chapter 2). In one study, researchers examined over 700 donated brains of older adults who had died. In many brains with Alzheimer's abnormalities, elevated methylation levels, which reduce or silence a gene's impact, were linked to genetic markers of the disease and predicted extent of amyloid plaque buildup (De Jager et al., 2014). The next step is to identify factors that trigger gene methylation associated with the disease. Protective Factors Researchers are testing both drug and nondrug approaches to preventing or slowing the progress of Alzheimer's. Among promising drug therapies are compounds that interfere with amyloid and tau breakdown and that suppress brain inflammation resulting from these toxic proteins, which worsens neuronal damage (Bachstetter, Watterson, & Van Eldik, 2014; Lou et al., 2014). Insulin therapy, delivered via a nasal spray to the brain, helps regulate neuronal use of glucose (Ribarič, 2016). Research indicates that it has memory benefits and slows cognitive decline among older adults with mild cognitive impairment—diminished mental abilities that are noticeable to the affected person, friends, and family members but that do not affect capacity to carry out everyday activities, which commonly precede Alzheimer's. A "Mediterranean diet" emphasizing fish, unsaturated fat (olive oil), vegetables, and moderate consumption of red wine is linked to a 30 to 50 percent reduced incidence of Alzheimer's disease, to slower disease progression in diagnosed individuals, and also to a reduction in vascular dementia (which we will turn to next) (Lourida et al., 2013; Morris et al., 2015). These foods contain antioxidants and other substances that help promote the health of the cardiovascular and central nervous systems. Education and an active lifestyle are beneficial as well. The rate of Alzheimer's is reduced by more than half in older adults with higher education, though this protective effect is not as great for those with the APOE &4 gene (Beydoun et al., 2014). Some researchers speculate that complex cognitive activities of better-educated people lead to reorganization of brain areas devoted to cognitive processes and to richer synaptic connections, which act as a cognitive reserve, giving the aging brain greater tolerance for injury before it crosses the threshold into mental disability. In support of this view, compared to their less-educated counterparts, the highly educated display a faster rate of decline following an Alzheimer's or other dementia diagnosis, suggesting that they show symptoms only after very advanced brain deterioration (Karbach & Küper, 2016). Late-life cognitively stimulating social and leisure activities also protect against Alzheimer's and dementia in general (Bennett et al., 2006; Hall et al., 2009; Sattler et al., 2012). Finally, persistence, intensity, and variety of physical activity are associated with decreased risk of Alzheimer's and vascular dementia (Smith et al., 2013). Benefits are greatest for older people with the APOE &4 gene. Helping Alzheimer's Victims and Their Caregivers As Ida's Alzheimer's worsened, the doctor prescribed a mild sedative and an antidepressant to help control her behavior. Drugs that increase levels of the neurotransmitters acetylcholine and serotonin show promise in limiting challenging dementia symptoms—especially agitation and disruptiveness, which are particularly stressful for caregivers (National Institute on Aging, 2016). But with no cure available, family interventions ensure the best adjustment possible for the Alzheimer's victim, spouse, and other relatives. Dementia caregivers devote substantially more time to caregiving and experience more stress than do people caring for older adults with physical disabilities (Alzheimer's Association, 2016a). They need assistance and encouragement from extended-family members, friends, and community agencies. The Social Issues: Health box on the following page describes a variety of helpful interventions for family caregivers. In addition, avoiding dramatic changes in living conditions, such as moving to a new location, rearranging furniture, or modifying daily routines, helps people with Alzheimer's disease feel as secure as possible in a cognitive world that is disintegrating.

Sexuality in late adulthood

When Walt turned 60, he asked his 90-year-old Uncle Louie at what age sexual desire and activity cease. Walt's question stemmed from a widely held myth that sex drive disappears in late adulthood. Louie corrected this impression. "My sexual interest has never gone away," he explained to Walt. "I can't do it as often, and it's a quieter experience than it was in my youth. But Rachella and I have led a happy intimate life, and it's still that way." As in other surveys of large, nationally representative samples of U.S. older people, the National Social Life, Health, and Aging Project revealed an age-related decline in frequency of sexual activity—especially among women, who are less likely than men to be in a marital or other intimate relationship. At the same time, the majority of respondents attributed at least some importance to sex, and those who had been sexually active in the previous year mostly rated sex as "very" or "extremely" important. Consistent with these attitudes, most married older adults reported continued, regular sexual enjoyment. Nearly half of the oldest survey participants, ages 75 to 85, were sexually active, with more than 20 percent indicating that they engaged in some type of sexual activity (usually intercourse) at least two to three times per month (see Figure 17.3) (Karraker & DeLamater, 2013). Note that these trends are probably influenced by cohort effects: A new generation of older people, accustomed to viewing sexuality positively, will probably be more sexually active. The same generalizations we discussed for midlife apply to late life: Good sex in the past predicts good sex in the future, and continued sexual activity is linked to relationship satisfaction. Furthermore, using intercourse as the only measure of sexual activity promotes a narrow view of pleasurable sex. Even at the most advanced ages, there is more to sexuality than the sex act itself—feeling sensual, enjoying close companionship, and being loved and wanted. Both older men and older women report that the male partner is usually the one who ceases to interact sexually (DeLamater, 2012; Karraker & DeLamater, 2013). In a culture that emphasizes an erection as necessary for being sexual, a man may withdraw from all erotic activity when he finds that erections are harder to achieve and more time must elapse between them. Disabilities that disrupt blood flow to the penis—most often, disorders of the autonomic nervous system, cardiovascular disease, and diabetes—are largely responsible for dampening sexuality in older men. But as noted in Chapter 15, drug treatments can be helpful. Cigarette smoking, excessive alcohol intake, mental health problems such as persistent anxiety and depression, and a variety of prescription medications also lead to diminished sexual performance (DeLamater, 2012; DeLamater & Koepsel, 2014). The little evidence available on lesbian and gay older adults resembles findings on heterosexual individuals: Those who are married or in a committed relationship are more sexually active. And as sexual minority couples grow old, their focus shifts from sexual acts that lead to climax to those that convey deep affection, such as kissing, embracing, caressing, and sleeping together (Slevin & Mowery, 2012).

Sleep in late adulthood

When Walt went to bed at night, he usually lay awake for a half-hour to an hour before falling asleep, remaining in a drowsy state longer than when he was younger. During the night, he spent less time in the deepest phase of NREM sleep (see Chapter 3, page 83) and awoke several times. Older adults require about as much total sleep as younger adults: around seven hours per night. Yet as people age, they have more difficulty falling asleep, staying asleep, and sleeping deeply. Insomnia affects about half of older adults. The timing of sleep tends to change as well, toward earlier bedtime and earlier morning wakening (McCrae et al., 2015). Changes in brain structures controlling sleep and higher levels of stress hormones in the bloodstream, which have an alerting effect on the central nervous system, are believed to be responsible. Fortunately, there are ways to foster restful sleep, such as establishing a consistent bedtime and waking time, exercising regularly, and using the bedroom only for sleep (not for eating, reading, or watching TV). Older adults receive more prescription sedatives for sleep complaints than do people under age 60. Used briefly, these drugs can help relieve temporary insomnia. But long-term medication can make matters worse by inducing rebound insomnia after the drug is discontinued (Wennberg et al., 2013).