Evaluate biological explanations of scz (15)

• Para 1: dopamine hypothesis

  • P: One key biological explanation of schizophrenia is the dopamine hypothesis, which links abnormal dopamine activity to the disorder.
  • E: The dopamine hypothesis identifies hyperdopaminergia in the mesolimbic pathway, causing positive symptoms like hallucinations, and hypodopaminergia in the mesocortical pathway, contributing to negative symptoms like apathy (Davis et al 1991).
  • E: While antipsychotic drugs that block dopamine receptors can reduce positive symptoms, the partial effectiveness for negative symptoms suggests dopamine alone cannot explain the full disorder. Additionally, PET scans (Copolov & Crook, 2000) have failed to reliably detect differences in dopamine levels, making it hard to confirm causality.
  • L: This supports the idea that while biological theories are prominent, the dopamine hypothesis may only offer a partial explanation
• Para 2: genetic contributions

  • P: Biological explanations also include the genetic basis of schizophrenia.
  • E: Gottesman's family and twin studies show a clear pattern: the more genes shared with someone with schizophrenia, the higher the risk of developing it. Identical twins show a 48% concordance, compared to 17% in siblings.
  • E: However, the Schizophrenia Working Group (2014) identified over 100 genetic loci involved, highlighting that schizophrenia is polygenic and complex, with no single "schizophrenia gene".
  • L: This suggests genetics is important but cannot fully account for the disorder, leaving room for interaction with environmental or psychological factors.
• Para 3: Brain structure abnormalities

  • P: Structural abnormalities in the brain also support biological explanations.
  • E: Studies using MRI and CAT scans (e.g. Andreasen, 1988; Weinberger, 1979) show that people with schizophrenia often have enlarged ventricles and cortical atrophy, indicating brain tissue loss.
  • E: However, these abnormalities are not exclusive to schizophrenia - they also occur in bipolar and schizoaffective disorders (Roy et al, 1998). Furthermore, antipsychotic medication itself may contribute to brain tissue loss (Lyon et al., 1981), making it hard to separate cause from effect.
  • L: While structural differences are consistent with a biological explanation, they may be a consequence of the illness or its treatment, rather than the cause.
• conclusion

  In light of recent evidence, biological explanations have become dominant due to advances in neuroimaging and genetics. However, their inability to fully account for all symptoms, along with issues of causality, suggests they may overshadow but not replace psychological accounts completely.