interactionist approach

• diathesis-stress model:

  • result of interaction between bio (diathesis) + environmental (stress) influences
  • both vulnerability + stress are needed to develop disorder
• diathesis-stress:

  • diathesis = evidence for role of genetics but concordance rates arent 100%
  • stress = stressful life events can trigger condition e,g sexual/physical abuse
• meehl's model:

  • original diathesis stress model - diathesis entirely genetic, one schizogene, led to development of schizotypic personality
  • if person lacks schizogene no amount of stress can trigger condition
  • in carriers of gene, chronic stress through childhood specifically schizophrenogenic mother can cause development
• modern understanding:

  • many genes create genetic vulnerability e.g ripke 108
  • modern view = range of factors including psychological trauma can become diathesis
  • read et al - early trauma alters developing brain e.g child abuse - HPA system can be overactive, making it vulnerable to later stress
• modern understanding of stress:

  • stress can be seen psychological in nature but also includes anything that can trigger disorder (houston et al)
  • cannabis = stressor, increases risk of schizo up to 7x as it interferes with dopamine system, most dont develop just after smoking so must also be other factors
• treatment:

  • combining antipsychotics + cbt, unusual to treat with cbt alone
  • britain = standard practice to treat with combination, US = conflict between biological + psychological models led to slower adaptation of interactionist approach
• EVALUATION: original diathesis stress model is oversimplified

  • multiple genes cause vulnerability no single schizogene, stress comes in different forms not solely family dysfunction
  • vulnerability can be result of early trauma not genes, houston et al - sexual trauma vulnerability, weed trigger
  • theory is reductionist, issue rectified in newer models
• EVALUATION: support for effectiveness of combination treatments

  • tarrier et al -randomly allocated 315 patients to med + cbt, med + supportive counselling + control group (meds only)
  • 2 combo groups showed lower symptom levels + no difference in rates of hospital readmission
  • clear practical advantage to adopting interactionist approach
• EVALUATION: dont know how diathesis stress works

  • strong evidence to suggest underlying vulnerability coupled with stress can cause schizophrenia - unclear how it results in disorder
  • mechanisms by which symptoms appear + how stress + vulnerability produce them is not understood
  • diathesis stress is too vague + cant provide a complete account of approach