SCHIZOPHRENIA: Diathesis-Stress Model

Question 1

What is the Diathesis for SZ ?

Answer 1

Entirely genetic. Genes are assumed to cause neurochemical abnormalities that in turn, result in increased risk of SZ. If a person does not have a genetic vulnerability, no amount of stress would lead to SZ.

Question 2

What is the Stress in SZ?

Answer 2

Negative psychological experience. e.g. dysfunctional parents and stressful life events. It is thought that diathesis and stress add together in some way to produce SZ.

Question 3

What is the additive nature of diathesis and stress?

Answer 3

In several ways stress and diathesis can combine to lead to onset of SZ. Relatively minor stressors may lead to onset for an individual who is highly vulnerable, or a major stress event may lead to the same result in a person low in vulnerability. Whatever the combination, this idea pre-supposes additivity, they add together in some way to get a SZ result.

Question 4

Who conducted a study into the Diathesis-Stress model within SZ patients?

Answer 4

Tienari et al (2004)

Question 5

What was the aim of Tienari et al’s study?

Answer 5

To see whether genetic factors moderate susceptibility to environmental risks associated with adoptive family functioning. Two-tailed hypothesis.

Question 6

What was the procedure of Tienari et al’s study?

Answer 6

1. Checked hospital records to identify women who’d had a psychotic episode. They’d noted kids given up for adoption
2. 145 high-risk adoptees compared with 158 ‘control’ adoptees
3. Both groups assessed after 12 years and followed up at 21 years. Family functioning also assessed.
4. Interviewers were kept blind about status of the biological mother to avoid investigator effects.

Question 7

What were the findings of Tienari et al’s study?

Answer 7

• 303 adoptees were looked at
• 14 developed SZ
• 11 of these were from high risk group (3 in control)
• Healthy adoptive family environment significantly reduced chance of SZ for high risk people
• Adoptive family stress predicted SZ development in high risk groups but not in control

Question 8

What was the conclusion of Tienari et al’s study?

Answer 8

Diathesis-stress. There is an interactive relationship between biological risk and environmental stress. The presence of both affects the other to produce an effect larger than the sum of both. SZ is caused by an interaction between nature and nurture factors