Antidepressants: partial response in chronic depression.

Although most studies of chronic depression show significant improvements with antidepressants versus placebo, the average Hamilton Depression Rating Scale results attained in the active-treatment group range between 10 and 14, suggesting that many patients only partially responded and failed to reach premorbid levels of symptom remission. Studies on the fate of these patients suggest that they are much more vulnerable to relapse, work impairment and suicide. Thus, partial response may be one form of treatment resistance, falling between total failure of response in a minority of patients, and a tendency to relapse or recur despite adequate maintenance treatment. Further study is needed to address the problem of improving the quality of response and attempting to reduce the detrimental effects of depressive illness in terms of relapse and recurrence.