Sz explanations

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  • Sz
    • Positive
      • Delusions
        • Grandeur
        • Reference
        • Control
        • persecution
      • Thought Disorder
        • loose/clang associations
      • Heightened sensitivity to sensations and hallucinations
        • auditory hallucinations
      • Inappropriate affect
    • Negative
      • Poverty of Speech- Alogia
        • Poverty of content
        • Thought blocking
      • Blunted/ Flat affect
      • Disturbances of volition
      • Disturbed relationships
    • Psychomotor
      • Catatonic rigidity/excitement
    • Paranoid
    • Catatonic
      • rare- not true category?
    • Disorganised
    • Undifferetiated
      • Vague- ill-defiined
    • Residual
    • Explanations
      • Biological
        • Family studies
          • Gottesman and Shields- Parent 5.6% Siblings 10.1%
        • Twin studies
          • Gottesman and Shields- Mz- 46% Dz- 14%
            • 46% for Mz shows contribution of genotype
            • Lytton- Mz twins reared similarly therefore nuture play part
          • Small sample
          • Environment-both twins don't always develop Sz
        • Adoption studies
          • Heston- 47 Sz mothers 16%
          • May be genetic predisposition to the disorder
          • Tienara 150 with  Sz  mothers  =10% 185 with non Sz mothers --> 1%
      • Biochemical
        • Dopamine hypothesis
          • only responsible for +ve symptoms
          • too simple. Breier- other neurotransmitters eg Serotonin associated with Sz
        • 2nd theory- more D2 receptors in Sz brains
          • Pearlson et al- PET scans show D2 receptors increase
          • Seeman et al- PET, 6x density of D4 receptors (subtype of D2)
          • Cause of pathology or effect of neuroleptic drugs taken?
      • Neuroanatomical
        • Jernigan et al- significant cell loss in Limbic System (subcortical structure)
        • Nasrallah et al- gender differences in thickening of fibres in the Corpus Callosum reversed in Sz
        • Szeseko et al- asymmetry in tempero- parietal region of the cortex less evidence in Sz
        • Raz and Raz- reduced brain tissue and enlarged ventricles- 1/2 the sample had enlarged ventricles- effect size of 0.6
          • May be linked to major functional abnormalities
        • Suddath et al- 15 disconcordant Mz twins. Sz twin had smaller Bilateral Hippocampus in 14/15 pairs and larger ventricles and less brain tissue
          • when genotype controlled for- less decreased brain volume in Sz twin
        • Liddle- underactivity of cerebral blood blow (CBF) in tempero frontal areas of the cortex with Sz- "Hypofrontality"
        • McGuire- CBF with auditory hallucinations- increased blood flow to Broca's area
        • -ve Lewis- 18 studies found no sig link between enlarged ventricles and negative symptoms
      • Socio-Cultural
        • Labelling
          • Thomas Szasz- labelling is "medicalisation of madness"
          • Scheff- breaks residual rules- labelled mentally ill, influences behaviour of person and others to them so fits label- self-fulfilling prophecy
          • Rosenhan- easy to be misdiagnosed with Sz
            • unethical? but had to mislead doctors
          • -ve only accounts for how symptoms are maintained- not cause or treatment
          • -ve ignores genetic evidence
          • -ve trivialises serious disorder
        • Family dysfunction
          • bateson et al- saying one thing/ body lan + tone different- double bind. don't trust own feelings
          • Lidz et al- family socialisation theory
            • Schismatic- competition for affection of family members
            • Skewed- dominating/ submissive. encouraged to follow dominant- impairs cog + social devel
          • Brown Carstairs and Topping- high expressed emotion EE, high relapse
            • Brown et al- high EE 58% relapse, low EE 10%
      • Diathesis stress model
        • lots of possible aetiological factors- may be predisposition

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