Antidepressant treatment in bipolar versus unipolar depression

Objective: Antidepressant responses were compared in DSM-IV bipolar and unipolar depression. Method: The authors analyzed clinical records for outcomes of antidepressant trials for 41 patients with bipolar depression and 37 with unipolar depression, similar in age and sex distribution. Results: Short-term nonresponse was more frequent in bipolar (51.3%) than unipolar (31.6%) depression. Manic switching occurred only in bipolar depression but happened less in patients taking mood stabilizers (31.6% versus 84.2%). Cycle acceleration occurred only in bipolar depression (25.6%), with new rapid cycling in 32.1%. Late response loss (tolerance) was 3.4 times as frequent, and withdrawal relapse into depression was 4.7 times less frequent, in bipolar as in unipolar depression. Mood stabilizers did not prevent cycle acceleration, rapid cycling, or response loss. Modern antidepressants, in general, did not have lower rates of negative outcomes than tricyclic antidepressants. Conclusions: The findings suggest an unfavorable cost/benefit ratio for antidepressant treatment of bipolar depression.