Aetiologies of depression

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  • Created by: marniefes
  • Created on: 28-01-16 13:47

Physiological explanations-Brain chemistry

  • Low levels of the neurotransmitters serotonin and noradrenaline cause negative thinking.
  • SSRIs (selective serotonin reuptake inhibitors) raise serotonin levelsby blocking reuptake and have been found to lift the mood of someone with depression
  • Low levels of noradrenaline in the urine of those with depression
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Physiological explanations-Hormones

  • High levels of stress hormone cortisol also linked to D
  • Research into Cushings syndrome (caused by high levels of cortisol) show that it is linked to low levels of serotonin and depression
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Physiological explanations-Brain Structure

  • Brain scans that people with depression often have an overactive amygdala, the emotional centre of the brain
  • This could explan the over-emotional state of people with depression
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Physiological explanations-Genes

  • Many people with depression have a faulty 5-HTT gene-the serotonin transporter gene
  • 17% of the general population will have depresison at some point in their life
  • DZ twins have a concordance rate of 20%
  • MZ twins have a concordance rate of 40-50%
  • If entirely genetic, this would be 100%
  • Biological parents of children with depression 8 times more likely to get depressed than adoptive parents
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Support for physiological explanations

  • McGuffin-Twin Study
  • 177 pairs of same sex MZ and DZ twins where one twin had been diagnosed with depression
  • 46% concordance rate for MZ twins, 20% concordance rate for DZ twins
  • TST strong genetic aetiology
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Methodology of physiological explanations

  • The twin, adoption adn brain research it is based on is objective, scientific and thus reliable
  • Effect of IV (MZ or DZ twin) on DV (risk of developing depression) enables controlled comparisons to be made
  • Evaluation: MZ twins are often treated more similarly than DZ twins
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Weakness of physiological explanations

  • Deterministic
  • Individuals have no control over hormones, genes or neurotransmitters
  • TST pessimistic 
  • Evaluation: SSRIs like prozac can raise serotonin levels
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Psychological explanations-Distorted thinking

  • A cognitive idea is that depression is caused by nagative and distorted thinking
  • Beck found depressed people tend to have negative schemas 
  • He developed the negative triad: pessimistic view of themselves, the world and the future
  • Beck believed this was caused by criticism from parents/teachers in early childhood
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Psychological explanations-Learned helplessness

  • Developed from Seligman's research with dogs
  • People who try but fail to control unpleasant life events like abuse learn to feel helpless
  • They do not learn coping strategies to cope with stressful life events like unemployment
  • This can lead to depression
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Support for psychological explanations

  • Langer and Rodin-enabling old people to make decisions had a positive effect on mental and physical health
  • Increased happiness, decreased helplessness and therefore depression
  • TST aetiology is closely related to learned helplessness
  • Could be used by social services to improve nursing homes
  • Shah and Waller found that people suffering from depression are more likely to describe their parents as affectionless than non-depressed people
  • TST criticism from parents can cause depression
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Methodology of psychological explanations

  • Based on unstructured interviews
  • Provide depth and insight and thus high on validity
  • However not consistent or reliable
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Weakness of psychological explanations

  • Reductionist
  • Only emphasises negative thinking and learning
  • Neglects genetics and brain chemicals
  • TST oversimplified view of depression
  • Diathesis-stress model: born with a genetic tendency but it takes lack of control over life to trigger it
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Applications

  • Depression is based on both nature and nurture explanations
  • Research is vital as it can lead to effective treatments
  • E.g. research into serotonin led to development of SSRIs, reseach into negative thinking led to CBT
  • The combination of these treatments has improved the lives of many with depression
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