biological explanations of schizophrenia essay plan
- Created by: hannah
- Created on: 13-11-14 15:31
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- biological explanations of schizophrenia
- GENETICS
- 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.
- DOPAMINE HYPOTHESIS
- 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
- BRAIN STRUCTURE
- 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?
- GENETICS
- CONCLUSION
- 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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