mind map of bio explanations for schizophrenia, may add the evolutionarry approach later

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  • Created by: alice
  • Created on: 12-12-12 16:27
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    • Genetics
      • Gottesman (1991) ---Concordance rates between relatives. 2 schizophrenic parents =46%, 1 schizophrenic parent =13% and siblings =9%. however could be due to rearing patterns.
      • Twin studies
        • Joseph (2004) calculated the concordance rates for MZ and DZ twins from all the data prior to 2001. MZ twins =40.4% and DZ twins =7.4%
          • MZ concordance rates were lower in later research, especially those that used 'blind diagnosis'. However, still MZ rates significantly higher than DZ
        • Assumption of twin studies that the environments of MZ and DZ twins are the same. DZ twins often treated more as individuals, MZ twins referred to as 'the Twins' treated more similarly, also more likely to experience 'identity confusion'
      • Adoption Studies
        • Tienari et al. (2000) --- 12 (6.7%) of the 164 adoptees with biological schizophrenic mothers also diagnosed. 4 (2%) of the 197 control adoptees diagnosed
        • Assumption of adoption studies that the parents who adopt children from a schizophrenic genetic background are the same as those who adopt children with a normal biological background.
        • Most adoption studies looking into schizophrenia broaden the definition of schizophrenia to non-psychotic schizophrenia spectrum disorders to get significant results
    • The Dopamine hypothesis
      • High levels of Dopamine
        • Wise and Stein (1973) ---found low levels of Dopamine Beta hydroxylase in schizophrenics who had died in accidents
        • Jackson (1986) ---found no evidence of higher dopamine activity in schizophrenics
      • Amphetamines
        • Timmons and Hamilton (1990) ---report high doses result in healthy people displaying behaviour resembling schizophrenia
        • Janowski et al. (1972) --- low doses in normal controls produced slight agitation. In schizophrenics a substantial worsening of symptoms
      • Anti-psychotics
        • Haracz (1982) ---found elevated dopamine levels in postmortems of schizophrenics who had taken medication shortly before death. Schizophrenics not on medication had normal levels
        • Barlow and Durand (1995) ---report that chlorpromazine reduces schizophrenic symptoms in 60% of cases. most impact on positive symptoms, not on negative
        • Davis (1978) ---found it takes weeks for the drugs to work, even though dopamine activity gets blocked immediately
      • Parkinson's disease
        • Timmons and Hamilton (1990) ---found very few schizophrenics suffer with parkinson's. Parkinsons is treated by increasing dopamine activity
        • Grilly (2002) --- found that some people taking L-dopa (raises dopamine levels) developed schizophrenic type symptoms
    • Enlarged Ventricals
      • Torrey (2002) on average the ventricals of a person with schizophrenia are 15% bigger than normal
      • Bornstien et al. (1992) --- schizophrenics with large ventricals are more likely to display negative rather than positive symptoms and respond poorer to anti-psychotics
      • Copoloy and Crook (2000) ---meta-analysis of over 90 studies with CT scans revealed a substantial overlap between schizophrenic and control populations in ventrical size
      • Lyon et al (1991) ---found that as the dose of anti-psychotic medication increased, the density of brain tissue decreased leading to enlarged ventricals


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