Depression
Definitions

Genetics

  • While depression is popularly considered to be due to life experiences and/or personality factors, there is in fact, strong evidence for significant genetic predisposition towards developing depression.
  • Studies of twins have confirmed that depression can be inherited. The genetic risk of developing clinical depression is about 40%, with the remaining 60% being due to factors in the individual’s own environment. Depression is unlikely to occur without life events, but the risk of developing depression as a result of some such event is strongly genetically determined. It is unlikely that any one contributing gene will be identified.
  • While the genetic risk to depression is now being clarified, the specific genes and traits inherited are yet to be identified. It may be that some of the genetic risk is to melancholic depression and, as well, to certain personality ‘styles’ that increase the chance of developing non-melancholic depression.
  • Relevant to this, there have been a number of reports of genes associated with particular personality characteristics. For example, genes have been identified that seem to be associated with novelty-seeking behaviour, and others that are linked to high anxiety levels (e.g the short arm of the SEROTONIN TRANSPORTER gene).
  • Though the genetics of depression are complex and progress is be expected to be slow, identification of genes that predispose a person to depression is a strong and growing area of research.