AO3

• One strength of the interactionist approach to schizophrenia is evidence supporting the role of both vulnerability and triggers in a large-scale study. by Tienari et al. (2004)
• Tienari et al (2004) investigated the impact of both genetic vulnerability and a psychological trigger (dysfunctional parenting)

  • followed 19,000 Finnish children whose biological mothers had been diagnosed with SZ
  • In adulthood this high genetic risk group were compared to a control group of adoptees without a family history of schizophrenia (low genetic risk)
• Tienari study

  • 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 SZ, but only in the high genetic risk group
  • This shows a combination of genetic vulnerability and family stress can lead to greatly increased risk of SZ
• One limitation of the original diathesis-stress model is oversimplicity
• Original model that portrayed diathesis as a single schizogene and stress as schizophrenogenic parenting is simplistic
• Multiple genes in multiple combinations influence diathesis
• Stress also comes in many forms, including but not limited to dysfunctional parenting
• Houston et al. (2008) childhood sexual abuse emerged as the major influence on underlying vulnerability to schizophrenia and cannabis use as the major trigger
• One 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 SZ has been the combination of drug treatment and psychological therapies
• Studies show that combining treatments enhances their effectiveness. Tarrier et al. (2004) randomly allocated 315 participants to:

  (1) medication + CBT

  (2) medication + counselling

  (3) control group (medication only)
• Tarrier et al. findings

  Px in the two combination groups showed lower symptoms following the trial than the medication-only group, though there was no difference in hospital readmission.
• Tarrier et al. strength means there is a practical advantage to adopting an interactionist

  approach to schizophrenia in terms of superior treatment outcomes.
• Counterpoint to Tarrier et al

  • Jarvis and Okami (2019) 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
  • Therefore we cannot automatically assume that the success of combined therapies means interactionist explanations are correct
• SZ is more commonly diagnosed in urban than rural areas. This statistic is sometimes used to justify the interactionist position, as it assumes that urban living is more stressful than rural and therefore city living acts as a trigger.

  However, it may simply be that schizophrenia is more likely to be diagnosed in cities, or that people with a diathesis for schizophrenia (e.g. teenagers abused as children) tend to migrate to cities.