(10 Interactionist approach to explaining and treating SZ

The diathesis-stress model

sees schizophrenia as a result of a combination of psychological/environmental and biological/genetic influences.

The symptoms of schizophrenia are triggered when significant stressors (the ‘stress’) in a person’s life are combined with a biological vulnerability (the ‘diathesis’) to the disorder.

What is the Diathesis part of the Diathesis Stress model?

research into twins has shown us that schizophrenia has a genetic component in that MZ twins have a higher concordance rate than DZ twins.

However, in about 50% of cases where one identical twin has schizophrenia the other does not develop it.

Candidate gene could be a diathesis

What is the Stress part of the Diathesis Stress model?

environmental stresses that may trigger schizophrenia come in various forms eg childhood trauma or the stresses of urbanised living or drug use..

The additive nature of diathesis and stress

The model suggests that diathesis and stress add together in some way to produce schizophrenia. It could be that someone with a high vulnerability only requires relatively minor stressors to develop schizophrenia, whereas someone with a low vulnerability may require a major stressful event.

Tienari et al(2004)

• 19,000 Finnish adopted children whose biological mothers had been diagnosed with sz

• In adulthood this high risk group were compared to a control group of adoptees

• It was found that high EE in adoptive families was strongly associated with the development of sz, but only in the high risk group

Diathesis - genetic disposition

Stress - adoption / EE

Interactionist treatment - combination therapy

Treatment should combine antipsychotic medication with CBT

This will have a higher level of effectiveness than one therapy alone

Evaluation of Diathesis-stress Model: nature vs nurture

Nature or nurture as single explanations are limited

Interactionism is a better explanation which considers the limitations of just a nature or nurture explanation

Evaluation of Diathesis-stress Model: reductionsist

The original diathesis-stress model is too simple; multiple genes in multiple combinations influence diathesis, and stress comes in many forms (e.g. can be biological as well as psychological)

E.g. Houston (2008) saw sexual abuse as the major vulnerability and cannabis use as the major trigger