Aetiologies of Schizophrenia

Anmerkungen:

• Aetiology = the study of the causes of diseases

1. for a diagnosis of schizophrenia to be given, patients have to have had +2 positive/negative symptoms for +1 month period, and had continuous signs of disturbance for +6 months
2. Biological: Genes
   1. means that a gene(s) for schizophrenia can be passed down from parents to children
   2. Twin studies

      Anmerkungen:

      • Concordance rate (CR) - the rate at which the other twin develops symptoms
      1. Rosenthal (1962) - studied female identical quadruplets, all 4 girls developed schizophrenia although they differed in terms of age of onset and their precise symptoms
         1. suggests that schizophrenia is genetic
         2. however, the girls had a terrible upbringing; both parents showed clear signs of instability; their childhood was disrupted due to the inability of the parents to properly care for them
            1. this supports the idea of genes as maybe the parents were slightly schizophrenic
               1. however, if parents were unstable, they could've created an unstable environment
      2. Gottesman (1991) - CR between MZ was 48% and 17% for DZ

         Anmerkungen:

         • Means that if one identical twin has schizophrenia, there is a 48% chance that the other twin will also have it
      3. however, CR's only reflect environmental differences as MZ are treated more similarly and experience more 'identity confusion'
         1. however, Gottesman points out that the CR's for twins reared apart and reared together are almost the same, suggesting a biological basis
      4. if schizophrenia is completely due to genetic factors, then CR should be 100%
   3. Adoption studies
      1. high CR with birth families = genetic basis
      2. high CR with adopted families = environmental factors
      3. Tienari (2000) - 6.7% of 164 adoptees who's biological mothers had schizophrenia, had schizophrenia; higher than the control group
         1. supports genetics
         2. however, children who are at a high genetic risk tend to do well if their adopted family provide a supportive environment; suggests that the environment and genes work together
      4. children are often placed in adopted homes that are similar to their birth family; confuses the issue of genes and environment
3. Psychological 1: Psychodynamic Approach
   1. Freud believed that schizophrenia emerged due to a conflict between the parts of the personality; the ego is overwhelmed by the id or superego
      1. as a result, the ego regresses back to infancy
      2. individual has delusions of self importance (like a child); fantasies become confused with reality as the ego tries to get control; hallucinations and delusions will emerge
   2. Freud argued that schizophrenics are driven by strong sexual impulses; helps explain why schizophrenia often develops in late adolescence
   3. however, no scientific evidence, doesn't explain it biologically, schizophrenic behaviour is not similar to infantile behaviour as it develops in adulthood
4. Psychological 3: Stress / Life Events
   1. Birley (1968) - after studying people who experienced schizophrenia, if they had a subsequent attack it was found that they reported 2x as many stressful life events compared with a healthy control group
   2. Day (1987) found that schizophrenics tended to have experienced a number of stressful life events in the few weeks before the onset of schizophrenia
   3. however, van Os (1994) reported no link between life events and the onset of schizophrenia
      1. patients were equally likely to have had a major life event or not in the 3 months prior to the onset of their illness