Prophylactic treatment of depression: a public health issue.

The majority of depressive illness is a chronic and relapsing, frequently occurring illness, which carries significant social and economic consequences for the sufferer. Depression is also associated with increased morbidity and mortality from physical illness and suicide. Long-term antidepressant treatment is needed for at least 6 months after the resolution of the symptoms of an acute episode to consolidate recovery. In recurrent depression, treatment over a much longer period is required to reduce the risk of a new episode occurring. It is clear from the prophylactic studies, which require careful and appropriate methods, that some half of the recurrent episodes of depression are preventable by adequate prophylactic treatment with antidepressants. This effect has been clearly demonstrated with some of the newly introduced 5-HT uptake inhibitors. The disadvantages of long-term treatment have to be weighed against the risks and costs, personal, social and economic, of the illness.