Risk of Suicidal Behavior With Antidepressants in Bipolar and Unipolar Disorders

Objective: To examine the risk of suicidal behavior (suicide attempts and deaths) associated with antidepressants in participants with bipolar I, bipolar II, and unipolar major depressive disorders.

Design: A 27-year longitudinal (1981-2008) observational study of mood disorders (Research Diagnostic Criteria diagnoses based on Schedule for Affective Disorders and Schizophrenia and review of medical records) was used to evaluate antidepressants and risk for suicidal behavior. Mixed-effects logistic regression models examined propensity for antidepressant exposure. Mixed-effects survival models that were matched on the propensity score examined exposure status as a risk factor for time until suicidal behavior.

Setting: Five US academic medical centers.

Results: Analyses of 206 participants with bipolar I disorder revealed 2,010 exposure intervals (980 exposed to antidepressants; 1,030 unexposed); 139 participants with bipolar II disorder had 1,407 exposure intervals (694 exposed; 713 unexposed); and 361 participants with unipolar depressive disorder had 2,745 exposure intervals (1,328 exposed; 1,417 unexposed). Propensity score analyses confirmed that more severely ill participants were more likely to initiate antidepressant treatment. In mixed-effects survival analyses, those with bipolar I disorder had a significant reduction in risk of suicidal behavior by 54% (HR = 0.46; 95% CI, 0.31-0.69; t = −3.74; P < .001) during periods of antidepressant exposure compared to propensity-matched unexposed intervals. Similarly, the risk was reduced by 35% (HR = 0.65; 95% CI, 0.43-0.99; t = −2.01; P = .045) in bipolar II disorder. By contrast, there was no evidence of an increased or decreased risk with antidepressant exposure in unipolar disorder.

Conclusions: Based on observational data adjusted for propensity to receive antidepressants, antidepressants may protect patients with bipolar disorders but not unipolar depressive disorder from suicidal behavior.