biological explanation

    Cards (6)

    • genetic basis
      • runs in families
      • strong relationship between degree of genetic similarity and shared risk of sz
      • mz twins = 48% and dz twins = 17%
      • candidate genes are individual genes that increase the risk of developing sz
      • polygenic = combination of genes can give a risk
      • aetiologically heterogenous = different combinations of factors can give a risk
      • 108 genetic variations associated with sz e.g genes that code for dopamine
    • dopamine hypothesis
      • neurotransmitters work differently in someone with sz, particularly dopamine
      • hyperdopaminergia in the subcortex = high levels of dopamine in the subcortex e.g excess in brocas causes speech poverty
      • hypodopaminergia in the cortex = low levels of dopamine in the prefrontal cortex can cause negative symptoms
    • neural correlates
      • negative symptoms = abnormality of ventral straitum involved with avolition
      • positive symptoms = lower activation levels in superior temporal gyrus and anterior cingulate gyrus can cause hallucinations
    • strength
      • adoption studies show that children of people with sz are still at heightened risk even if adopted by families with no sz history
      • very strong evidence for genetic vulnerability
      • genetic susceptibility needed along with other environmental factors
    • mixed evidence for dopamine hypothesis
      • dopamine agonists increase dopamine and give people sz symptoms even though they dont have sz
      • antipsychotic drugs reduce dopamine activity
      • both suggest important role for dopamine
      • dopamine doesnt provide a full explanation as some candidate genes code for other neurotransmitters not just dopamine
      • may be down to a neurotransmitter called glutamate
    • role of mutation
      • mutation in parental dna by viral infection can give a risk when theres an absence of family history
      • positive correlation between paternal age (causes the mutation) and developing sz
      • 0.7% in fathers under 25 and 2% in fathers over 50
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