Aetiologies of unipolar depression

Paragraph 1: Biological explanations:

  • This suggests that depression could be a consequence of genetic factors. Evidence to support this comes from family, twin and adoption studies.
  • For example a study carried out by McGuffin et al (1996) found that concordance rates of 46% for MZ twins, compared to 30% of DZ twins. A problem with this concordance rate is that it can't entirely be genetic, as twins share the same environment and go through the same major life events. The concordance rate is nowhere near 100% which suggests that although there may be a gentic component in the onset of depression, it is not entirely genetic.
  • A criticism is that the biological theories are biologically deterministic as they suggest we are unable to change our genetics.
  • Another criticism is that the theories are also reductionist as they ignore environmental factors such as major life events.
  • However the diathesis-stress model suggests that some people possess a genetic predisposition to depression. This may be triggered by environmental stressors.
  • Evidence to support this model comes from research which has found that although depression is linked to negative link events, individuals from genetically high-risk groups are the most likely to become depression.
  • The advantage of this theory is that it is an interactionist approach because it takes into account both sides of the nature and nurture debate.
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P2: Biological explanations:

  • One explanation of depression is that it is caused by deficiencies of noradrenaline and serotonin (neurotransmitters). Support from this comes from the fact that depression is effectively treated using drugs that will increase the availability of serotonin and noradrenaline in the brain.
  • However anti-depressants are not effective in the treatment of all cases of depression. Anti-depressants also have effects on many other neurochemicals (just not noradrenaline and serotonin) so these may not be the only neurotransmitters involved in depression. It is unclear though whether deficiencies in neurotransmitters cause depression or are a consequence of it.
  • A major criticism of biological theories is that they are reductionist because they ignore thought processes.
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P3: Cognitive explanation:

  • The cognitive explanation suggests that depression is caused by a negative 'depressogenic' schema.
  • This is characterised by what Beck called the 'cognitive triad'. This involves the negative thoughts about the self, the world and the future. As a consequence, they expect to fail and blame themselves when they do.
  • Craighead (1977) found that depressed people tend to recall information in negative terms and recall their failures more often than their sucesses. This supports the concept of negative schemas.
  • However evidence does not support the idea that such schemas proceeded the onset of depression.
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P4: Behavioural explanations:

  • Behavioural psychologists have tried to explain depression in terms of learned helplessness.
  • Seligman (1974) suggested that people who learn that they are unable to do anything to improve their situation (learned helplessness) may lose motivation and give up. As a consequence they may start to show symptoms of depression,.
  • Weiss et al (1970) found that animals with learned helplessness had lower levels of noradrenaline than controls. This suggests that stressors which create learned helplessness can also cause some of the biochemical changes associated with depression.
  • However, while behavioural theories emphasise the role of nurture, they can be accused of under-emphasising the role of nature. Furthermore, they are determinist because they suggest that we are simply a product of our learning environment, which we have very little control over.
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P5: Behavioural & Cognitive combined:

  • Seligman reformulated his theory by combining elements of the cognitive and behavioural models to produce the 'Hopelessness Theory of Depression' - suggested that when people experience failure they usually try to attribute a cause to the failure.
  • A maladaptive style used by people with depression who attribute a cause to that failure - attributing negative events to internal characteristics e.g. I'm stupid (stable attribution) or e.g. I always do badly on tests (global attribution).
  • Selignman found that students who hadn't acheived their desired grades in an exam showed signs of depression. Those who had made stable and global attributions remained depressed for longer than those who did not. Although, the findings of this study seems to support the view that attributional style may be an important factor in depression, it lacks population validity as the participants were students not clinicially depressed patients.
  • If hopelessness is the cause of depression, it should precede the onset of depression, although there is not much evidence to support this.
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P6: Conclusion:

  • In conclusion, perhaps the best explanation for depression depends on each individual case. In other words, perhaps in some cases, people are innately predisposed to depression. In other cases, the situation they find themselves in, their upbringing or the thinking styles that they acquire are the real cause of their depression.
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