interactionist approach

• diathesis stress model


  sz result of an interaction between biological (innate) and environmental (external) influences - family studies suggest people have varying levels of inherited genetic vulnerability - whether or not a person develops sz partly determined by internal vulnerability and partly amount and level of stress experienced over their lifetime
• diathesis


  strong evidence suggests genes have key role in development of sz - mz twins share 100% same genes at greater risk of developing sz than dz twins - in 50% of mz twins where one has the disorder, the other doesn't - indicates environmental factors play a role in determining whether a biological vulnerability develops into a disorder
• stress


  stressful life events that can trigger sz take variety of forms like childhood trauma - Varse found children who experience severe trauma before age of 16 were 3 times as likely to develop sz in later life compared to general population - living in urban environments increases risk of sz, possible result of stressful living conditions of densely populated environments - breakdown in relationships and academic pressure could trigger sz
• treatment


  acknowledges both biological and psychological factors so compatible with biological and psychological treatments - model recommends combining antipsychotic medication and psychological therapies (CBTp)
• INTERACTIONIST EVALUATION - support for dual role

  Tienari - assessed adopted children whose biological mother suffered sz compared to control group with no genetic risk - found parenting style characterised as high levels of criticism and low levels of empathy implicated in development of sz but only for children with genetic vulnerability not control group - suggests genetic vulnerability and family related stress important in development and poor parenting can be a source of stress
• INTERACTIONIST EVALUATION - diathesis may not be exclusively genetic

  argued increased risk of sz originally thought to come from genetics but could be from brain damage caused by environmental factors - Verdoux estimated risk of sz for individuals who experienced birth complications 4 times greater than those with none - diathesis not always due to genetics
• INTERACTIONIST EVALUATION - stress may not be exclusively environmental

  stress seen as psychological in nature but modern versions argue biological factors can trigger stress and sz like illness and drug use - cannabis key stressor increases risk of sz by 7 times according to dose as it interferes with dopamine system - approach incomplete and limited
• INTERACTIONIST EVALUATION - don't know exactly how diathesis and stress work

  strong evidence to suggest underlying vulnerability coupled with stress can lead to sz we don't fully understand mechanisms which symptoms appear and how vulnerability and stress interaction produce them - approach is incomplete and limited
• INTERACTIONIST EVALUATION - effectiveness of treatment combination

  Tarrier - after patients randomly allocated to medication and CBT group, medication and counselling group or control group, patients in 2 combined groups showed lower levels of symptoms than control group - show practical advantage to adopting interactionist approach to sz treatment for patients - takes holistic view to explaining and treating sz