Alzheimers Unit 1

Other risk factors

Age, family history and genetics are all risk factors we can't change. Research is beginning to reveal clues about other risk factors that we may be able to influence. There appears to be a strong link between serious head injury and future risk of Alzheimer's. It's important to protect your head by buckling your seat belt, wearing a helmet when participating in sports and proofing your home to avoid falls.

What is Alzheimer's disease?

Alzheimer's is a disease of the brain that causes problems with memory, thinking and behavior. It is not a normal part of aging. Alzheimer's gets worse over time. Although symptoms can vary widely, the first problem many people notice is forgetfulness severe enough to affect their ability to function at home or at work, or to enjoy lifelong hobbies. The disease may cause a person to become confused, get lost in familiar places, misplace things or have trouble with language. It can be easy to explain away unusual behavior as part of normal aging, especially for someone who seems physically healthy. Any concerns about memory loss should be discussed with a doctor.

Family history

Another risk factor is family history. Research has shown that those who have a parent, brother or sister with Alzheimer's are more likely to develop the disease than individuals who do not. The risk increases if more than one family member has the illness.

Dementia

Dementia is a general term for the loss of memory and other intellectual abilities serious enough to interfere with daily life.

Plaques

Plaques are deposits of a protein fragment called betaamyloid that build up in the spaces between nerve cells.

Tangles

Tangles are twisted fibers of another protein called tau that build up inside cells.

What goes wrong in the brain

The brain has 100 billion nerve cells (neurons). Each nerve cell connects to many others to form communication networks. In addition to nerve cells, the brain includes cells specialized to support and nourish other cells. Groups of nerve cells have special jobs. Some are involved in thinking, learning and memory. Others help us see, hear, smell and tell our muscles when to move. Brain cells operate like tiny factories. They receive supplies, generate energy, construct equipment and get rid of waste. Cells also process and store information and communicate with other cells. Keeping everything running requires coordination as well as large amounts of fuel and oxygen. Scientists believe Alzheimer's disease prevents parts of a cell's factory from running well. They are not sure where the trouble starts. But just like a real factory, backups and breakdowns in one system cause problems in other areas. As damage spreads, cells lose their ability to do their jobs and, eventually, die.

The role of plaques and tangles

The brains of individuals with Alzheimer's have an abundance of plaques and tangles. Though autopsy studies show that most people develop some plaques and tangles as they age, those with Alzheimer's tend to develop far more. They also tend to develop them in a predictable pattern, beginning in the areas important for memory before spreading to other regions. Scientists do not know exactly what role plaques and tangles play in Alzheimer's disease. Most experts believe that they disable or block communication among nerve cells and disrupt processes the cells need to survive.

how alzheimer's affects the brain

The changes that take place in the brain begin at the microscopic level long before the first signs of memory loss

Age

The greatest known risk factor for Alzheimer's disease is increasing age. Most individuals with the illness are 65 and older. One in nine people in this age group has Alzheimer's. Nearly one-third of people age 85 and older have Alzheimer's.

Familial Alzheimer's and genetics

Two categories of genes influence whether a person develops a disease: risk genes and deterministic genes. Risk genes increase the likelihood of developing a disease but do not guarantee it will happen. Deterministic genes directly cause a disease, guaranteeing that anyone who inherits one will develop a disorder.

causes and risk factors

While scientists know that Alzheimer's disease involves the failure of nerve cells, why this happens is still unknown. However, they have identified certain risk factors that increase the likelihood of developing Alzheimer's.

Down syndrome dementia

develops in people born with extra genetic material from chromosome 21, one of the 23 human chromosomes. As individuals with Down syndrome age, they have a greatly increased risk of developing a type of dementia that's either the same as or very similar to Alzheimer's disease.

Creutzfeldt-Jakob disease

is the most common human form of a group of rare, fatal brain disorders known as prion diseases. Misfolded prion protein destroys brain cells, resulting in damage that leads to rapid decline in thinking and reasoning as well as involuntary muscle movements, confusion, difficulty walking and mood changes.

Normal pressure hydrocephalus

is a brain disorder in which excess cerebrospinal fluid accumulates in the brain's ventricles, causing thinking and reasoning problems, difficulty walking and loss of bladder control.

Korsakoff syndrome

is a chronic memory disorder caused by severe deficiency of thiamine (vitamin B-1). It is most commonly caused by alcohol misuse, but certain other conditions can also cause the syndrome.

Mixed dementia

is a condition in which abnormalities characteristic of more than one type of dementia occur simultaneously. Symptoms may vary, depending on the types of brain changes involved and the brain regions affected, and may be similar to or even indistinguishable from those of Alzheimer's or another dementia.

Vascular dementia

is a decline in thinking skills caused by conditions that block or reduce blood flow to the brain, depriving brain cells of vital oxygen and nutrients. These changes in thinking skills sometimes occur suddenly following strokes that block major brain blood vessels. It is widely considered the second most common cause of dementia after Alzheimer's disease

Frontotemporal dementia (FTD)

is a group of disorders caused by progressive cell degeneration in the brain's frontal lobes (the areas behind the forehead) or its temporal lobes (the regions behind the ears).

Huntington's disease dementia

is a progressive brain disorder caused by a defective gene. It causes changes in the central area of the brain, which affect movement, mood and thinking skills.

Dementia with Lewy bodies

is a type of progressive dementia that leads to a decline in thinking, reasoning and independent function due to abnormal microscopic deposits that damage brain cells.

Parkinson's disease dementia

is an impairment in thinking and reasoning that eventually affects many people with Parkinson's disease. As brain changes gradually spread, they often begin to affect mental functions, including memory and the ability to pay attention, make sound judgments and plan the steps needed to complete a task.

Posterior cortical atrophy (PCA)

is the gradual and progressive degeneration of the outer layer of the brain (the cortex) located in the back of the head (posterior). It is not known whether PCA is a unique disease or a possible variant form of Alzheimer's disease.