The Interactionist Approach To Schizophrenia

What is the interactionist approach?

An approach to explaining schizophrenia that acknowledges that there are biological, psychological and social factors involved.

What do biological factors include?

Genetic vulnerability and neurochemical and neurological abnormality.

What do psychological factors include?

Stress

What do social factors include?

Poor quality interactions in the family.

What is the diathesis-stress model?

An interactionist approach to explaining behaviour where diathesis means vulnerability and stress means a negative experience. IT says that both a vulnerability to schizophrenia and a stress-trigger are necessary in order to develop the disorder.

What was Meehl’s model?

This was the original diathesis-stress model where diathesis (vulnerability) was entirely genetic, the result of a single ‘schizogene‘ leading to the idea of a biologically based schizotypic personality, one characteristic of which is sensitivity to stress.

What did Meehl say?

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 the presence of a schizophregenic mother could result in the development of the disorder.

How was our understanding of diathesis changed?

It is now clear that many genes appear to increase genetic vulnerability only slightly, there is no ‘schizogene‘.

What do modern views of diathesis include?

A range of factors beyond the genetic, including psychological trauma - so trauma becomes the diathesis rather then the stressor.

What did Read et al. propose?

A neurodevelopmental 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. For example, the HPA system can become overactive, making a person more vulnerable to later stress.

In the original diathesis-stress model of schizophrenia, what was stress seen as?

Psychological in nature, in particular related to parenting.

Although psychological stress including that resulting from parenting may still be considered important, what does a modern definition of stress include?

Anything that risks triggering schizophrenia. Much of the recent research into factors triggering an episode of schizophrenia has concerned cannabis use.

In terms of the diathesis-stress model, why is cannabis a stressor?

Because it increases the risk of schizophrenia by up to seven times according to dose. This may be because it interferes with the dopamine system. However, most people do not develop schizophrenia after smoking cannabis because they lack the requisite vulnerability factors.

What does the interactionist model of schizophrenia acknowledge?

Both biological and psychological factors in schizophrenia and is therefore compatible with both biological and psychological treatments. 

What is the interactionist model associated with combining?

Antipsychotic medication and psychological therapies, most commonly CBT.

What does Turkington et al. point out?

That it is perfectly possible to believe in biological causes of schizophrenia and still practice CBT to relieve psychological symptoms. However, this requires adopting a psychological model - it is not possible to adopt a purely biological approach and tell people diagnosed with schizophrenia that their condition is purely biological and that there is no psychological significance to symptoms, and then to simultaneously treat them with  CBT.

In Britain, what is it increasingly standard practice to treat people diagnosed with schizophrenia with?

With a combination of antipsychotic drugs and CBT as opposed to the US where there is a history of conflict between psychological and biological models of schizophrenia.

What are the strengths of the interactionist approach to schizophrenia?

• Support for vulnerability and triggers.

• Real-world application.

How is support for vulnerability and triggers a strength of the interactionist approach to schizophrenia?

In a large-scale study, Tienari et al. investigated the impact of both genetic vulnerability and a psychological trigger (dysfunctional parenting). The study followed 19,000 Finnish children whose biological mothers had been diagnosed with schizophrenia. In adulthood, this high genetic risk group were compared to a control group of adoptees without a family history of schizophrenia (low genetic risk).Adoptive parents had been assessed for child-rearing style and it was found that high levels of criticism, hostility and low levels of empathy were strongly associated with the development of schizophrenia, but only in the high genetic risk group.

What does the support for vulnerability and triggers show about the interactionist approach to schizophrenia?

This shows that a combination of genetic vulnerability and family stress can lead to greatly increased risk of schizophrenia.

How is real-world application a strength of the interactionist approach to schizophrenia?

A further strength of the interactionist approach is in the combination of biological and psychological treatments. A practical application of acknowledging biological and psychological factors in schizophrenia has been the combination of drug treatment and psychological therapies. Studies show that combining treatments enhances their effectiveness.

For example, Tarrier et al. randomly allocated 315 participants to

(1) medication + CBT, (2) medication + counselling, or (3) control group (medication only). Participants in the two combination groups showed lower symptoms following the trial than the medication-only group, though there was no difference in hospital readmission.

What does the real world application mean for the interactionist approach to schizophrenia?

That there is clear practical advantage to adopting an interactionist approach to schizophrenia in terms of superior treatment outcomes.

What is the counterpoint to the real world application?

Jarvis and Okami point out that saying that a successful treatment for mental disorder justifies a particular explanation is the logical equivalent of saying that because alcohol reduces shyness, shyness is caused by lack of alcohol. This logical error is called the treatment-causation fallacy.

What does the real world application mean for the interactionist approach to schizophrenia?

We cannot automatically assume that the success of combined therapies means interactionist explanations are correct.

What is the limitation to the interactionist approach to schizophrenia?

• Diathesis and stress are complex.

How is diathesis and stress being complex a limitation of the interactionist approach?

It is now clear that the original model that portrayed diathesis as a single schizogene and portrayed stress as schizophrenogenic parenting is hopelessly simplistic. Multiple genes in multiple combinations 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 by Houston et al., in which childhood sexual abuse emerged as the major influence on underlying vulnerability to schizophrenia and cannabis use as the major trigger.

What does diathesis and stress mean for the interactionist approach?

That there are multiple factors, both biological and psychological affecting both diathesis and stress, supporting the modern understanding of both diathesis and stress.