biological explanations of schizophrenia essay plan

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  • Created by: hannah
  • Created on: 13-11-14 15:31
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  • biological explanations of schizophrenia
      • evidence for inheritance - runs in families
      • gene mapping compared genetic material from families with high and low incidence, results show several genes involved In predisposal.
      • risk of development increases to 48% in monozygotic twins from dizygotic if one twin has sz.
      • kendller found that 1st degree relatives of sz person is 18x more likely to develop the disorder than the rest of the population
      • janicak found most twin studies show 48% concordance rate for mz twins and 17% for dz
        • not 100% concordance - other factors involved - shared env
      • gottesman found the closer the degree of relatedness, the more likely the development of sz - 2 parents sz = 46% chance, 1 parent = 13% chance, sibling = 9% chance
      • gottesman and shields used maudsley twin register, found 7 out of 12 twins reared apart were concordant for sz
        • rules out env factors as similar concordance when reared together
        • small sample - not representative - cant generalise
        • env trauma of separation may have had an impact, not 100%, some factors overlooked
      • tienari, 164 finish adoptees with biological sz mothers, 11 diagnosed, control group(non sz mother) only 4 diagnosed.
        • control group higher than normal - env trauma of adoption impacting development of sz
        • rules out env bc developed  sz despite upbringing. supports genes theory as higher than average 1% in population.
      • solely nature debate - reductionist, ignores env impacts/nurture, 48% shows not just genes are involved
      • research is empirical and objective - scientific credibility.
      • deterministic - self fulfilling prophecy - proposing there is nothing you can do to compensate for your genetic inheritance - no free will or choice.
      • excess of neurotransmitter operation brain = sz
      • messages from neurons that transmit dopamine fire too often = symptoms
      • biochemical abnormalities detectable in sz brains
      • sz have higher no. of d2 receptors = more binding = more firing neurons. dopamine neurons play a major role in attention and perception = symptoms
      • grilly found people taking drug L-dopa to increase dopamine levels developed sz symptoms
      • phenothiazines bind to d2 receptors, block transmission of nerve impulses =reduced attention deficit
      • wong looked at PET scans showing dopamine receptor intensity in the caudate nuclei bring greater in those with sz than controls
        • objective scientific measure - empirical
        • cause or effect? could be result of having sz not cause
      • reductionist - overlooks family or env impacts, narrow focus
      • removes blame from patient and family - ethical theory
      • ventricles =cavities in brain that supply nutrients and remove waste, using brain imaging techniques found sz people have enlarged ventricles
      • torrey found 15% larger than normal and tend to display negative symptoms, have greater cognitive disturbances and poorer response to traditional antipsychotics
      • young used MRI scans and found differences in brain structure between sz and controls, particularly in asymmetry - in control the amygdala was smaller on the left, in sz the asymmetry was lacking
        • objective measurements - is psy a science debate
      • meyer - lindenberg examined brain activity in sz during a working memory task - pre frontal cortex showed reduced activity reflecting poor performance.
        • also dopamine levels were increased suggesting dysfunction of pre frontal cortex is linked to dopamine abnormalities - dopamine hypothesis combination - strong evidence for biological cause + less reductionist
      • cause or effect?
    • biology alone not a complete explanation
    • diathesis stress model more applicable, as 50% twin concordance shows other factors must be involved.




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