Factors associated with initial treatment response with antidepressants in bipolar disorder

IntroductionControversy in antidepressant (AD) use in bipolar depression relies in its potential induction of mood switches and ineffectiveness. Responders to acute AD add-on treatment maintain response with continued treatment, whilst partial/non-responders fail to reach remission despite continuation treatment. We aimed to identify response predictors to acute AD addition in bipolar depression in order to optimize treatment choice in bipolar depression and avoid unnecessary AD exposure of people unlikely to respond.MethodsTwo hundred and twenty-one DSM-IV-TR depressed bipolar – type I and II – patients were treated with AD on an observational study. AD response was defined as an at least 50% drop from baseline of their HDRS17 score after 8 weeks of treatment. One hundred and thirty-eight patients (138, 62.4%) fulfilled response criteria (RI) whilst 83 patients (37.6%) did not (NRI). In all cases AD therapy was on top of previously prescribed stabilizers and/or atypical antipsychotics.ResultsRI patients were more likely to have had previous response to ADs, whereas NRI had a higher number of previous mood switches with ADs during past depressive episodes. Psychotic symptoms were more frequent amongst RI, whilst lifetime history of atypical depression was more frequent amongst NRI. NRI had more total, depressive, and hypomanic, but not manic or mixed, episodes in the past than RI. Analyzed through a logistic regression, higher previous response to ADs and lower rate of past hypomanic episodes in RI were the variables explaining intergroups (RI vs. NRI) differences.DiscussionTaking into account the proper caution in the use of Ads in bipolar disorder, there is a subgroup of bipolar patients who might benefit from adjunctive Ads. Looking at specific clinical factors during the course of the illness could help physicians in deciding whether to use an antidepressant in a bipolar depressed patient already treated with mood stabilizers.