Genetic explanations of schizophrenia

• The general public have a 1 % chance of developing schizophrenia but this increases to 9 % if you have a sibling with schizophrenia.

  With an identical twin this increases to 48 %.
• The genetic explanation states there is a genetic predisposition to schizophrenia through the inheritance of certain candidate genes.

  Ripke stated there are 108 gene variations implicated with the development of Sz showing the condition is polygenic and aetiologically heterogenous.

  All the genes implicated affect the transmission of dopamine.
• AO3

  :)

  Research support comes from Gottesman and Shields who found that children with both parents diagnosed with schizophrenia had a heritiability rate of 46 % and with 1 Sz parent they had a rate of 13 %.

  Those with a sibling diagnosed had a rate of 9 % which shows the degree to which genetics play a factor in the development of Sz.

  Supports the idea of familial heritability increasing the risk of Sz which increases the validity of the explanation.
• AO3

  :)

  Further research support for the genetic explanation of schizophrenia comes from Tienari et al.

  They followed 19,000 adopted Finnish children who all had diagnosed biological mothers (high genetic risk).

  They compared the children to a control group with a low genetic risk.

  They found that despite the fact the children grew up with adoptive families they still had a heightened risk of developing Sz, showing signs of low levels of empathy and increased hostility.

  This therefore provides evidence for the genetic basis of schizophrenia and thus increases its validity.
• AO3

  :(

  Critics argue that the genetic explanation may be biologically reductionist because it reduces the explanation down into simple candidate genes, discounting the influence of cognitive and environmental factors which may infact increase the risk of the development of SZ.

  Research to support this comes from Hilker who found a 33 % concordance rate for monozygotic twins.

  However if this were simply a definitive genetic predisposition then surely the concordance rates should be 100 % which therefore shows that there are environmental factors at play, not accounted for.