Interactionist approach

• Higher diatheses levels means a higher vulnerability to SZ, likely related to genes
• Possible diatheses:

  Genetic factors

  Physical trauma prenatally or during birth

  Structural abnormalities of the brain

  Abnormalities in the neurotransmitter systems
• Possible stressors:

  Chronic psychology and social stressors

  Family environment with high expressed emotion

  Drug use, especially marijuana
• Meehl stated that if a person does not have the “ schizogene “, then no amount of stress could lead to schizophrenia. However we know the presence of social factors could be enough to result in the condition e g the schizophrenogenic mother
• We know now there is no schizogene - it is polygenic
• Many genes appear to increase genetic vulnerability to SZ
• Stress - anything that risks triggering schizophrenia
• Cannabis can be a stressor and increases the risk of SZ 7 x. This is because it interferes with the dopamine system.
• Tienari ( 2004 ) looked at hospital records for nearly 20,000 women admitted to Finnish psychiatric hospitals between 1960 and 1979. The list of those diagnosed with SZ was checked to find those mothers who had one or more of their children adopted away
• Tienari ( 2004 ). 145 adopted away offspring were compared to 158 adoptees without the genetic risk 12 years later. They assessed family functioning in the adoptive families. Interviewers did not know which group the person belonged to.
• Tienari ( 2004 ) found that being in a healthy adoptive family protected even those with a high risk for SZ

  Adoptive family stress was a significant predictor of development of SZ in high risk adoptees
• Tienari ( 2004 ) found that 14 / 303 adoptees had developed SZ, and 11 / 14 were from the high risk group
• Varese ( 2012 ) found that children who experience severe trauma before the age of 16 were three more times likely to develop SZ in later life compared to the general population. The level of trauma was also a factor.
• Additivity - diathesis and stress add together to produce the disorder. Someone with low vulnerability and high stressors may develop SZ, as well as someone with high vulnerability may be triggered by minor stressors