The importance of the interactionist approach in explaining and treating schizophrenia
Rather than seeing the development of schizophrenia as being due to a specific biological or psychological explanation, it is better to regard the mental disorder as being a product of several interacting factors, both biological and psychological. This is the interactionist approach, which encompasses the diathesis-stress model, where a schizophrenic episode is perceived as being triggered or worsened when environmental stressors (stress) combine with an individual’s level of biological vulnerability (diathesis) to developing the condition. The interactionist approach sees schizophrenia as having an underlying genetic component, not from possessing a single ’schizophrenia gene’, but from the cumulative effect of several genes, with the more of these genes an individual possesses, the greater their biological vulnerability to developing the mental disorder. However, even having a high genetic vulnerability does not mean an individual will develop schizophrenia. For that to happen environmental stressors, such as family dysfunction, substance abuse, critical life events, etc., have to occur, with the greater the genetic vulnerability to developing schizophrenia, the easier it is for environmental stressors to trigger an episode. Biological vulnerability can also be due to abnormal brain functioning or biochemistry. The interactionist approach also sees a combination of biological and psychological treatments as being more effective than any single biological or psychological treatment.
Fig 12.5 The flu theory of schizophrenia perceives the disorder as occurring due to an interaction of biological and environmental factors
Murray (1996) assessed the interactionist approach by reviewing evidence concerning the degree to which pregnant mothers contracting flu impacted on individuals’ vulnerability to developing the disorder in later life. Data were collected by assessing how many schizophrenics’ mothers had contracted flu while pregnant and at which point in the pregnancy they had contracted flu. It was found that children who were born after flu epidemics where their mothers had contracted the disease while pregnant, especially in the second trimester (pregnancy months 4—6), had an 88 per cent increased chance of developing schizophrenia than children born in the same time period whose mothers had not contracted flu. Exposure to flu during the second trimester is suspected of causing defects in neural brain development, which leads to increased vulnerability to schizophrenia due to brain damage, which has a knock-on effect on dopamine functioning. This illustrates how schizophrenia could result from an interaction of factors.
• Walker (1997) reported that schizophrenics have higher levels of cortisol than non-sufferers and that cortisol levels are related to severity of symptoms, with stress-related increases in cortisol levels heightening genetic-influenced abnormalities in dopamine transmission that underpin vulnerability to schizophrenia, triggering the onset of the disorder. This illustrates the interaction of biological and environmental factors in the development of schizophrenia in line with the diathesis-stress model.
• Barlow & Durand (2009) reported that a family history of schizophrenia, indicating a genetic link, coupled with a dysfunctional stressor elevated the risk of developing schizophrenia, supporting the diathesis-stress model.
• Guo et al. (2010) reported that patients in the early stages of schizophrenia who receive a combination of antipsychotics and a psychological therapy have improved insight, quality of life and social functioning and are therefore less likely to discontinue treatment or relapse than those taking antipsychotics alone, illustrating the value of combined treatments.
The differential susceptibility hypothesis extends the diathesis-stress model to include positive as well as negative environments. This sees exposure to positive factors, such as having a loving, supportive family background, as reducing the chances of someone developing schizophrenia.
As schizophrenia often has both biological and psychological components, combined treatments are often desirable, where biological treatments like drugs address the biological elements and psychotherapeutic treatments the psychological elements.
Although combining therapies increases the cost of treatment, the increase in effectiveness of treatment can make combination therapies more cost effective in the long term.
Stressors that may contribute to a risk of developing schizophrenia include biological, environmental, psychological, and social factors. However, it is not known precisely how these risks contribute to the diathesis-stress interaction for any one person because specific causes for schizophrenia may differ between individuals.
Combination treatments can have a down side too: patients receiving CBT sometimes interpret the side effects of simultaneous drug treatment in a delusional manner, increasing their mistrust and resistance to further treatment.
Combination treatments, although desirable, cost more than individual treatments and so may not be made available to all patients.
The main application of research into the interactionist approach is in developing tailor-made combination therapies that suit an individual’s specific needs, for example initial treatment with drugs followed by family therapy for a patient with dysfunctional family relationships.