Interactionist Approach

• A range of biological, psychological and societal factors are involved in the development of schizophrenia
• A Diathesis-stress model is an Interactionism approach to schizophrenia: the result of both an underlying (genetic) vulnerability (Diathesis) and an environmental trigger (stress)

  Both are necessary for the onset of schizophrenia
• Meehl’s Diathesis stress model (1962)

  Vulnerability to schizophrenia is entirely genetic, as genes cause an increase of dopamine that result in an increased risk for schizophrenia

  If there is no genetic vulnerability, no amount of stress would lead to schizophrenia

  Meehl proposed this was the result of a single ‘schizogene’ - However, a more modern approach is that many genes appear to increase genetic vulnerability

  The stress (trigger) for schizophrenia is negative psychological experience, eg dysfunctional parents and major life events
• Meehl’s Diathesis Stress Model (1962)

  For example, child abuse can seriously affect brain development: the HPA system can become over active, making the person much more vulnerable to alter stress

  Cannabis is thought to increase the risk of SCZ by 7x because of its affect on dopamine
• Vassos et al (2012)

  The risk of schizophrenia i the most urban environments was estimated to be 2.37x higher than in the most rural environments

  However, research has found no difference in mental health between rural and urban environments in women in New Zealand, which suggests the Diathesis Stress Model may not be assessing the impact of stress
• Treatment according to the Interactionism approach

  As the Interactionism model acknowledges both biological and psychological factors in schizophrenia, it is associated with combining antipsychotic medication (targeting dopamine) and psychological therapies (commonly CBTp)

  • More common in the UK than US
• Strength - Evidence for the role of vulnerability and triggers - Tienari et al (2004)

  Investigated the combination of genetic vulnerability and parenting style (trigger)

  Adoptees from 19,000 Finnish mothers with SCZ between 1960 and 1979 were followed up

  Adoptive parents were assessed for child-rearing style

  Rates of schizophrenia were compared to those in a control group of adoptees without genetic risk
• Strength - Evidence for the role of vulnerability and triggers - Tienari et al (2004) findings

  Child-rearing style with high levels of conflict and low levels of empathy were part of the development of SCZ - only for the children with high genetic risk

  Suggests both genetic vulnerability and family related stress are important in the development of SCZ - genetic vulnerable children are more sensitive to parenting behaviour

  Very strong support for the importance of Interactionism approach to SCZ, including idea that poor parenting is a possible source of stress
• Weakness - original model is over-simplified

  Classic model of a single schizogene and schizophrenic parenting stems as the major source of stress is now known to be over-simple

  Multiple genes increase vulnerability, each having a small effect on its own - there is no schizogene

  Stress can come in many forms, including dysfunctional parenting - therefore, vulnerability and stress to not have one single source

  Vulnerability can be the result of early trauma as well as genetic makeup, and stress can come in many forms
• Weakness - The original model is over-simplified

  James Houston et al (2008) - childhood sexual trauma emerged as a vulnerability factor whilst cannabis was a trigger, showing evidence that the old idea of Diathesis as biological and stress as psychological has turned out to be over simple, this is a problem for the old idea of the Diathesis-stress but not for the newer months
• Strength - Support for the effectiveness of combinations as treatment

  Studies show an advantage to using combinations of treatment for SCZ

  Tarrier et al (2004) - 315 people with SCZ were randomly allocated to a medication + CBT group, medication + supportive counselling or a control group

  People in the two combination groups showed lower symptom levels than those in control group (medication only), although there was no difference in rates of rehospitalisation

  This shows that there is a clear practical advantage to using interactionist approach in the form of superior treatment outcomes