Partial remission, residual symptoms, and relapse in depression.

Partial remission from depression, with residual symptoms, is an important problem in depression. This paper reviews the frequency and features of this outcome, and its association with relapse. Residual symptoms occur in many depressed patients after acute treatment. They span the typical symptoms of depression, except those characteristic of severe disorders. Other persistent abnormalities include social dysfunction, dysfunctional attitudes, hypothalamic-pituitary-adrenal axis overactivity, shortened REM sleep latency, and mood lowering after tryptophan depletion. Associations of some of these with residual symptoms are not clear. There is growing evidence for similar residual symptoms in bipolar disorder, particularly bipolar depression. The most important consequence of residual symptoms is a much-increased risk of relapse, particularly in the first year. Residual symptoms are a strong indication for vigorous and longer than usual continuation of antidepressant treatment in order to prevent relapse. There is good evidence for the use of cognitive therapy as an adjunct.