Does recent mania affect response to antidepressants in bipolar disorder? A re-analysis of STEP-BD data

Background: One previous study suggested that the presence of a manic episode before bipolar depression is related to worse response to antidepressants. Method: To examine this effect in a larger sample, we used data from the large, multi-site STEP-BD study. We hypothesized that among persons treated with antidepressants for bipolar depression, manic or mixed episodes before depression onset (as compared to euthymia) would predict lower rate of recovery, more sustained depressive symptoms and higher rate of switching into mania/hypomania after antidepressant treatment of bipolar depression. 320 participants were available for analyses (140 male) diagnosed with bipolar I, bipolar II, cyclothymia, bipolar disorder not otherwise specified, or schizoaffective disorder bipolar subtype. Patients were randomly assigned to 3 treatment randomization strata (placebo, bupropion, and paroxetine) as adjuncts to mood stabilizers. Results: Analyses were conducted to examine the effect of episode status before the depressive episode on the degree of change in depressive symptoms at 3 and 6 months, the likelihood of depression recovery and the likelihood of anti-depressant induced switching. Presence of a manic episode before depression in patients with bipolar disorder did not significantly predict response to antidepressants. Limitations: The study was limited by a high rate of attrition, and consideration of only two antidepressant medications. Conclusions: Our findings are in agreement with other past studies suggesting that mania and depression may operate separately for those with bipolar disorder, with differential predictors of the onset and offset of mania versus depression. Future directions may consider vulnerability for these episodes separately.