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Biological Explanations - Coggle Diagram

- - - - If one parent has schizophrenia there is a 12% chance
      - If both parents have it there is a 40% chance
      - Implies that schizophrenia is polygenic.
- - - - To find out if there is a genetic basis for schizophrenia. Also, to replicate previous twin studies into schizophrenia to test their reliability. In particular, the researcher looks for concordance rates in MZ twins where one suffered from schizophrenia and compared these to concordance rates in DZ twins to see if there was a significant difference which would be explained by genes.
    - - In every category, there was a significant difference between MZ and DZ twins, with MZ twins being more likely to share a similar diagnosis of mental illness. The concordance was stronger for female twins than male twins and also stronger with more severe schizophrenia.
      - For severe schizophrenia (involving 2+ years in hospital), the concordance rate for MZ twins was 75%, but only 24% for DZ twins.
    - - The closer the genetic link, the more likely both twins are to show schizophrenic symptoms.
        
        However, the MZ concordance rate was significantly lower than 100%. This means that, despite their shared genotype, MZ twins do not always share schizophrenic symptoms.
        - This suggests that genetics is not the only cause of schizophrenia.
      - Conclude that genes may predispose a person towards but there needs to be an enviuromenal trigger. This is called the diathesis stress model put forward by Rosenthal 1963
      - …
        
        Critics point out that environment can lead to schizophrenia too: child abuse, neglect, bullying, drug and alcohol problems, all play a part. Often, if one twin suffers these things, the other one does too. However, there might be all sorts of reasons other than genes why one twin might "rise above" these difficulties but the other has a breakdown.
- - - - It is an important neurotransmitter that regulates mood and attention.
        
        It is linked to schizophrenia.
      - The Dopamine Hypothesis
        
        it was proposed by Arvid Carlosson and suggests that schizophrenia is caused by too much dopamine or too many dopamine receptors in the brain;
  - - - Increased dopamine activity and reduces schizophrenia like symptoms.
- - - - Patel et al 2010
        
        By using PET scans to asses dopamine levels in schizophrenia and normal individuals.
        
        Found lower levels of dopamine in the dorsolateral prefrontal cortex of schizophrenic patients compared to normal patients.
    - - Wang and Deutch 2008
        
        They induced dopamine depletion in the prefrontal cortex in rats.
        
        Found that you could reverse cognitive impairments using olanzapinem an atypical antipsychotic drug.
        
        Ague the reductionist issues with this study.