AO3

• Supporting research

  Gottesman - meta analysis of schizophrenics found a 48% concordance rates of 45% with monozygotic twins, 17% with dizygotic, and 1% with the general population. Tienari found adopted children who's mothers suffered schizophrenia were more likely to develop the disorder than adopted children who's mothers did not. Clinical and objective methods and meta analysis allows a large sample to be analysed increasing the generalisability and external validity of the results.
• Concordance rates are not 100% suggesting genetics can not provide a full comprehensive explanation for schizophrenia, additionally twins are usually brought up in similar environments therefore we cannot rule out external factors as an explanation on schizophrenia. This could be overcome by adoption studies however this would assume that children are not selectively placed and Joseph in 2004 found that prospective parents often receive information about the child prior to adoption, reducing the validity of the results.
• Tilo et al gave 6 non and 6 schizophrenics fMRI scans when they spoke and looked at Rorschach ink blocks found severity of their thought disorder was negatively correlated with level of activity in Wernicke brain area (coherent speech)
• Schizophrenics who mainly exhibit enlarged ventricles do not respond to medication suggesting it is an effect of long term suffering rather than it leading to disorder - unsure whether brain abnormalities found are caused by genetic factors or are a result of the disorder itself
• Drugs that decrease dopamine transmission lead to a reduction in symptoms (chlorpromazine)
• Lloyds et al says even if dopamine is a factor in onset it’s not a direct cause, could work alongside env factors (abnormal family situations)
• Dopamine hypothesis is too simplistic, several neurotransmitters may be involved eg serotonin and glutamate - no consistent difference in dop levels between schizophrenics and non schizophrenics so link is inconclusive - doesn’t explain why patients have a slow recovery when medication has instant effect on dopamine levels