Biological explanations of depression 

  • Created by: 08rmorris
  • Created on: 05-04-15 14:15
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  • Biological explanations of depression
    • Genetic factors
      • Being biologically relate to someone who has depression seems to increase a person's chase of developing it
      • Evidence for
        • McGuffin et al (1996) found that if one MZ  twin has MDD, then in 46% of cases the other twin would be diagnosed as well
          • For DZ twins the concordance rate is about 26%
        • Wender et al (1986) studied biological parents of adopted children who had MDD
          • the biological parents were 8X more likely to have depression than the children's adopted parents
      • Evidence against
        • The concordance rates found in family and twin studies aren't 100%, so genetics cant be the whole story. Environmental factors play a role
        • Genetic factors only seem to explain endogenous depression (caused by internal factors) - psychological factors seem to have more influence in development of reactive depression
    • Biochemical factors
      • Low levels of serotonin have been linked to depression
        • Kety (1975) developed the permissive amine theory, which states that serotonin controls the levels of the NT noradrenaline
          • A low level of serotonin cause the levels of noradrenaline to fluctuate
            • Low levels of noradrenaline then cause depression
            • high levels of noradrenaline cause mania
      • Evidence for
        • Anti-depressant drugs work by increasing the availability of seotonin at the synapses by preventing its reuptake or breakdown
          • This suggests that it's the low levels of serotonin that lead to depressive disorders
        • Post-mortems carried out on people who committed suicide have shown abnormally low levels of serotonin
          • Suggesting that this may have caused their depression
      • Evidence against
        • Just because anti-depressants relive the symptoms does not mean they treat the cause
        • Low levels of serotonin could be a result of depression not the cause
        • Psychological research has found alternative explanations for the cause of depression


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