Depression in older people is recognised as a major health problem affecting 10-15 per cent of the population. Older patients with depression rapidly lose their independence and rely heavily on care delivered by family, friends and the NHS. Prompt treatment of the disease is essential as more serious consequences of depression, such as physical illness can develop. Selective Serotonin Reuptake Inhibitors (SSRIs) are the mainstay of treatment; however, older patients are at greater risk of hospital admission due to serious side effects (falls and confusion) and in some patients SSRIs are ineffective.
Depression is caused by a reduction of a chemical in the brain called serotonin, which nerve cells use to communicate. A protein called SERT acts to decrease serotonin levels in the brain. Antidepressant drugs stop this protein working, restoring serotonin levels to normal. However, older people have less SERT for antidepressants to work on and this may compromise effective treatment and increase the risk of side effects. In addition, genetic differences in SERT and other proteins involved in serotonin communication have also been shown to further reduce treatment and exacerbate side effects. Antidepressants can take a number of weeks to work.
This research project investigated whether it was possible to identify older patients who will respond to antidepressants, using a simple genetic test. It is hoped that this will ensure appropriate therapy is not delayed, and minimise the chance of developing serious side effects.