A Level Psychology: Schizophrenia - The Diathesis-Stress Model

What is the interactionist approach?

- An approach that acknowledges that there are biological, psychological and social factors in the development of Sz

Why may you have to adopt an interactionist approach when treating Sz through the diathesis-stress model?

- Because it is not possible to adopt a purely biological approach and tell people diagnosed with Sz that there condition is purely biological and that there is no psychological significance to symptoms and then to simultaneously treat them with CBT

What has been found to trigger an episode of Sz?

- Cannabis use

What is one way of treating Sz with this model?

- Combining antipsychotic medication and psychological therapies, most commonly CBT

What are the biological factors involved in the development of Sz?

- Genetic vulnerability - Neurochemical and neurological abnormality

What did Read et all (2001) propose about trauma?

- He proposed a neurodevelopment model in which early trauma alters the developing brain - Early and severe enough trauma such as child abuse can seriously affect many aspects of brain development

What is the modern definition of stress in the diathesis-stress model?

- Includes anything that risks triggering Sz - It still includes parenting as important

Explain cannabis as a stressor in the diathesis-stress model

- It can increase Sz by up to 7x according to the dose - This may be because cannabis interferes with the dopamine system - However, most people do not develop Sz after smoking cannabis presumably because they lack the requisite vulnerability factors

How has our understanding of the diathesis-stress model now changed since Meehl's model?

- It is now clear that many genes each appear to increase genetic vulnerability only slightly, there is no single 'schizogene'

What is required if you believe in the biological causes of Sz and psychological treatment for Sz through the diathesis-stress model?

- It requires adopting an interactionist approach

What did the original diathesis-stress model say the diathesis was?

- It was entirely genetic, the result of a single 'schizogene'

Evaluation of the interactionist approach - Real-world application - Strength

- One further strength of the interactionist approach is the combination of biological and psychological treatment - A practical application of acknowledging biological and psychological factors in Sz has been the combination of drug treatment and psychological therapies - Studies show that combining treatments enhanced their effectiveness - Researchers randomly allocated 315 participants to 1) medication + CBT 2) medication + counselling or 3) a control group of medication only - Participants in the two combination groups showed lower symptoms following the trial than the medication only groups though there was no difference in hospital readmission - This means that there is a clear practical advantage to adopting an interactionist approach to SZ in terms of superior treatment outcomes

Evaluation of the interactionist approach - Diathesis and stress are complex - Limitation

- One limitation of the original diathesis-stress model is over simplicity - It is now clear that the original model that portrayed diathesis is a single schizogene and portrays stress as schizophrenogenic parenting is hopelessly simplistic - Multiple genes in multiple combined influence diathesis - Stress also comes in many forms, including but not limited to dysfunctional parenting - In fact, diathesis can also be influenced by psychological factors and stress can be biological as well as psychological - This is shown in a study where psychologists look at how childhood sexual abuse emerged as the major influence on underlying vulnerability to Sz and cannabis as the major trigger - This means there are multiple factors, both biological and psychological affecting both diathesis and stress, supporting the modern understanding of both diathesis and stress

Evaluation of the interactionist approach - Support for vulnerability and triggers - Strength

- One strength of the interactionist approach to Sz is evidence supporting the role of both vulnerability and triggers - Researchers investigated the impact of both genetic vulnerability and psychological trigger - The study followed 19,000 Finnish children whose biological mothers had been diagnosed with SZ - In adulthood, this high genetic risk group were compared to a control group of adoptees without a family history of Sz - Adoptive parents had been assessed for child-rearing style and it was found that high levels of critics, hostility and low levels of empathy were strongly associated with the development of Sz, but only in the genetic risk group - This shows that a combination of genetic vulnerability and family stress can lead to greatly increased risk of Sz

What are the social factors involved in the development of Sz?

- Poor quality interactions in the family

What was stress seen as in the original diathesis-stress model?

- Seen as psychological in nature, in particular related to parenting

What are the psychological factors involved in the development of Sz?

- Stress - Eg, life events and daily hassle

What does the diathesis-stress model suggest?

- That both vulnerability to Sz and a stress trigger are necessary in order to develop the disorder - According to this model the symptoms of Sz are triggered or made worse when significant stressors (the stress) in a person's life are combined with a biological vulnerability (the diathesis)

What did Paul Meehl propose about the diathesis-stress model?

- That if a person does not have the schizogene then no amount of stress would lead to schizophrenia - However in carriers of the gene, chronic stress through childhood and adolescence in particular in the presence of a schizophorgeneic mother, could result in the development of the disorder

What did Turkington et al (2006) believe about treatment of Sz?

- That is perfectly possible to believe in biological causes of Sz and still practise CBT to receive psychological symptoms

Whats another factor that can now act as a diathesis?

- Trauma, trauma becomes the diathesis rather than the stressor