interactionist approach to schizophrenia

• The diathesis stress model:

  • Believes that schizophrenia is the result of an interaction between biological and environmental influences 
  • Both vulnerability to schizophrenia and stress -trigger needed to develop schizophrenia 
• • Additivity - diathesis and stress add together in some way to on set schizophrenia - e.g minor stressors lead to the onset for someone who has high vulnerability. Or major stress event causes a similar reaction for someone with low vulnerability 
• Meehl's diathesis stress model (1962) -

  • The diathesis (vulnerability) is entirely genetic - single schizogene - led to biological schizotypic personality 
  • If you don’t have schizogene - there is no amount of stress that would cause schizophrenia 
  • Chronic stress through childhood and adolescence - particularly having a schizophrenogenic mother - could result in disorder 
• Modern understanding of diathesis

  • Ripke et al - provides evidence that there is no single schizogene - more genes increase vulnerability
  • Read et al - proposed a neurodevelopmental model - early trauma alters the developing brain (eg- child abuse) impacts development -eg-  H(hypothalamus)P(pituitary gland)A(adrenal gland) axis becoming overactive and more vulnerable to later stress 
• Modern understanding of stress 

  • Stress doesn’t have to be psychological 
  • Research has found that factors that increase the risk of triggering schizophrenia include cannabis use - cannabis users 7x more likely to develop schizophrenia 
  • Cannabis interferes with dopamine systems  - however not every cannabis user develops schizophrenia
• Modern understanding of stress 

  • Varese et al - children who experience severe trauma before 16 were 3x more likely to develop schizophrenia 
  • Vassos et al - meta-analysis - risk for schizophrenia in urban environments is 2.37x higher - possible more adverse living conditions in densely populated areas 
• supportive evidence for the interactionist approach: Teinari - 19000 Finnish children with biologically schizophrenic mothers (high genetic risk) compared with a control group of adoptees (low genetic risk). high degrees of expressed emotion associated with schizophrenia but only in the high genetic risk group. - This means that the combination of genetic and psychological elements was required for schizophrenia – supporting the idea of the diathesis stress model. 

  - gives the interactionist approach higher validity and credibility in terms of explaining schizophrenia 
• opposing evidence for interactionist approach: it is difficult to define ‘stress’ – it is subjective. Individuals have varying thresholds when it comes to stress – also we don't know when these stressors need to occur? (relating to diathesis stress) – unclear if stress is the trigger or the vulnerability. this suggests that the interactionist approach cannot explain how the interactions of stress and genes trigger schizophrenia – stress is too ambiguous
• applications of interactionist approach: Interactionist treatments- tarrier et al – randomly allocated 315 pps to drugs + cbtp, drugs + counselling or just drugs – patients in the combo groups showed lower symptoms than those just on drug therapies. - This means that the explanation can help in real life scenarios and so is accurate at explaining why schizophrenia develops - BUT... Economic impacts – combo treatments can cost the NHS a lot (more than just drug therapy)