Schizophrenia - The Interactionist Approach Flashcards
What are the key features of the interactionist approach?
- diathesis-stress model: vulnerability + trigger = schizophrenia
- Meehl’s model: gene + stress = schizophrenia
- modern understanding of diathesis
- modern understanding of stress
What is the diathesis-stress model?
Diathesis means vulnerability; stress in this context refers to negative psychological experiences.
The diathesis-stress model says both a vulnerability and a stress trigger are needed to develop schizophrenia.
What is Meehl’s model?
In the original diathesis-stress model, diathesis was entirely the result of a single ‘schizogene’.
Meehl (1962) argued that someone without this gene should not develop schizophrenia, no matter how much stress they were exposed to.
But a person who does have the gene is vulnerable to the effects of chronic stress (e.g. a schizophrenogenic mother).
The schizogene is necessary but not sufficient for the development of schizophrenia.
What is the modern understanding of diathesis?
It is now believed that diathesis is not due to a single ‘schizogene’. Instead it is thought that many genes increase vulnerability.
Also, diathesis doesn’t have to be genetic. It could be early psychological trauma affecting brain development.
For example, child abuse affects the hypothalamic-pituitary-adrenal system, making a child vulnerable to stress.
What is the modern understanding of stress?
A modern definition of stress (in relation to diathesis-stress) includes anything that risks triggering schizophrenia (including psychological stress).
For example, cannabis use can increase the risk of schizophrenia up to seven times depending on dose - probably because it interferes with the dopamine system.
What are the key features of treatment according to the interactionist approach?
- antipsychotic medication and CBT
- UK adopts more interactionist approach compared to US
How can you treat patients using antipsychotic medication and CBT?
Turkington et al. (2006) suggest it is possible to believe in biological causes of schizophrenia and still practise CBT to relieve psychological symptoms.
But this requires adopting an interactionist model - it is not possible to adopt a purely biological (no psychological significance to their symptoms) and then treat them with CBT.
Why does the UK adopt a more interactionist approach compared to the US?
In Britain it is increasingly standard practice to treat patients with a combination of drugs and CBT.
In the US there is more of a conflict between psychological and biological models of schizophrenia and this may have led to slower adoption of the interactionist approach.
What are the strengths of the interactionist approach to schizophrenia?
- support for the dual role of vulnerability and stress
- the usefulness of the interactionist approach in treatment
What are the weaknesses of the interactionist approach to schizophrenia?
- the original diathesis-stress model is too simplistic
- we don’t know exactly how diathesis and stress work
- the treatment-causation fallacy
What support is there for the dual role of vulnerability and stress?
Tienari et al. (2004) studied children adopted away from schizophrenic mothers. The adopted parents’ parenting styles were assessed and compared with a control group of adoptees with no genetic risk.
A child-rearing style with high levels of criticism and conflict and low levels of empathy was implicated in the development of schizophrenia but only for children with a high genetic risk.
This is very strong direct support for the interactionist approach - genetic vulnerability and family-related stress combine in the development of schizophrenia.
How is the interactionist approach useful in treatment?
Tarrier et al. (2004) randomly allocated 315 patients to:
- medication and CBT group
- medication and supportive counselling group
- control group.
Patients in the two combination groups showed lower symptom levels than those in the control group (medication only) - but no difference in hospital readmission.
Studies like this show there is a clear practical advantage to adopting an interactionist approach in the form of superior treatment outcomes.
Why is the original diathesis-stress model too simplistic?
Multiple genes increase vulnerability, each with a small effect on its own - there is no schizogene. Stress comes in many forms, including dysfunctional parenting.
Researchers now believe stress can also include biological factors. For example, Houston et al. (2008) found childhood sexual trauma was a diathesis and cannabis use a trigger.
This shows that the old idea of diathesis as biological and stress as psychological has turned out to be overly simple.
Why don’t we know exactly how diathesis and stress work?
There is strong evidence to suggest that some sort of underlying vulnerability coupled with stress can lead to schizophrenia.
But we do not understand the mechanisms by which symptoms of schizophrenia appear and how both vulnerability and stress produce them.
This does not undermine support for the approach, but it does mean we have an incomplete understanding of the actual mechanism.
What is the treatment-causation fallacy?
Turkington et al. (2006) argue the fact that combined biological and psychological therapies are more effective than either on their own does not necessarily mean the interactionist approach to schizophrenia is correct.
Similarly the fact that drugs help does not mean that schizophrenia is biological in origin. This error of logic is called the treatment-causation fallacy.
It means that the superior outcomes of combined therapies should not be over-interpreted in terms of evidence in support of the interactionist approach.
