The interactionist approach to schizophrenia

Diathesis stress model:

Both a vulnerability and stress trigger are needed to develop SZ.

‘Schizogene’ diathesis model:

Meehl’s model:

• Diathesis vulnerability was entirely genetic as a result of a ‘schizogene’.

• No amount of stress will cause a person without the gene to develop SZ.

• Stress in childhood with the gene could lead to SZ (e.g. schizophrenogenic mother).

The modern understanding of diathesis:

Ripke (2014) 108 genes implicated with SZ, not just one gene (polygenic).

Read (2001) diathesis can be other factors like psychological trauma. For example childhood trauma can lead to the hypothalamic-pituitary adrenal system can become overactive, leading to more vulnerability to stress.

The modern understanding of stress:

Psychological stress can also be in cannabis use. It increases risk SZ by 7x, but most people do not develop SZ after smoking cannabis so there are other factors.

Interactionist treatment:

Combining CBT and antipsychotics. Medication and CBT is more common in the UK compared to America.

Support for the role of vulnerability

Tienari (2004) investigated both genetic and psychological vulnerability. 19,000 Finnish children with biological SZ mothers compared to adoptee control group.

High levels of criticism, hostility and low levels of empathy = high genetic risk group.

Oversimplified original model

Houston (2008), investigated other forms of stress, found childhood sexual abuse emerged as the major influence on underlying vulnerability to SZ and cannabis use as the major trigger.

Real-world application

Combining treatments enhances effectiveness.

Tarrier (2004) randomly allocated 315 participants to

(1) medication + CBT

(2) medication + counselling,

(3) control group (medication only).

Combination groups = lower symptoms than 3. Though there was no difference in hospital re-admission.