AO3

• a strength is that PET scans have been used to assess dopamine levels in

  - schizophrenics and ‘normal’ people and found lower levels of dopamine in the prefrontal cortex in schizophrenics compared to the control group
• This demonstrates that

  -The negative and cognitive symptoms of SZ are thought to arise from a deficit of dopamine in the areas of the prefrontal cortex
• in support crespi identified

  -76 genes linked to schizophrenia.

  -This suggests that whilst there is evidence for a genetic explanation for SZ, it involves a combination of affected genes and is polygenic.
• A weakness is that 2/3 of sz

  -do not have any relatives with the disorder.

  -This would suggest that the genetic explanation is too simplistic and there may be other factors involved e.g. double bind theory-type of family dysfunction
• a weakness of the dopamine hyp is that

  -antipsychotic drugs which are meant to decrease dopamine levels actually increase them, as the neurones struggle to compensate for the sudden decrease.

  -This suggests that highlevels of dopamine maynot be a cause of SZ.
• however a strength of the dop hyp is that people who suffer from parkinson's disease

  have low levels of dopamine and take the drug L-dopa to raise levels of dopamine

  -raise it too much and they develop schizophrenic type symptoms (Grilly 2002).

  -This suggests that Excessive levels of dopamine causes Schizophrenia.