interactionist approach

what is the interactionist approach

• recognises biological + psychological factors = SZ

• rejects the idea SZ has one cause, and is instead an interaction between

  • biological vulnerability

  • environmental stressors

    • this is the diathesis-stress model

what is diathesis

• vulnerability

• a biological predisposition

  • inherited genes, early brain damage, birth complications

  • some people are more vulnerable to SZ than others

what is the stress

• the trigger

• environmental factors that activate the vulnerability 

  • childhood trauma

  • family dysfunction

  • drug abuse

development of SZ

• interactionist approach says SZ only develops when a vulnerability and stress occur together

meehl’s model 1962

• suggests a single “schizogene”

• if someone has this gene they are vulnerable

• if they experience chronic stress (especially from a SZ mother) the gene is triggered and they devleop SZ

• if they don’t have the gene, no amount of stress can lead to the development of SZ

  • early oversimplified version

modern understanding (post meehl model)

• no single gene

  • polygenic

• vulnerability comes from genes, brain abnormalities, or early trauma

• stress comes from any environmental factor

  • includes cannabis use

treatment implications

• interactionist approach supports a combo of treatments

  • antipsychotics + psychological therapy

  • research shows this is more effective than one or the other alone

evaluate the interactionist approach

• tienari et al 2004 finnsih adoption study

  • compared adoptees from mothers with SZ (genetic risk) with non-SZ mothers

  • raised in different adoptive families

  • high risk = more likely to develop it in high EE family

  • high risk in supportive family = less likely to develop SZ

    • supports diathesis-stress model

• tarrier et al 2004

  • drug + CBT = -50% psychotic experiences, 15% free of all positive symptoms

  • CBT = -15% psychotic experiences, 7% free of all positive symptoms

  • drug = no change

    • supports combined treatment

• the nature of stress and vulnerability is hard to measure

  • could be biological, psychological, or social

  • different studies define them differently 

  • too broad to predict who will develop SZ