Depression is a leading cause of disability that ultimately impacts on:
- Social support
- Daily functioning
- Physical health
- Cognitive functioning
Depression affects twice as many women as men with social and familial factors also increasing risk. High prevalence of major depressive disorder has been reported in nursing care homes (17-25%) with the prevalence of minor depression occurring in 8-16% of community-dwelling elderly. In developed countries, 20% of women will be affected with depression at some point in their life.
The latest anti-depressant drugs still work in a similar way to drugs developed 30 years ago and they only show response in 65% of patients. Treatment-resistant depression is, therefore, a major health issue that requires research to identify new drug targets. Major depression has been reported to have a heritability of between 31-42% and substantial evidence suggests that serotinergic neurotransmitter genes play a central role in its aetiology. Depression is a complex genetic trait and groups have reported that gene-gene and gene-environment interactions are likely to exist.