Cigarette smoking is associated with suicidality in bipolar disorder

Bipolar patients have markedly elevated rates of nicotine dependence (1, 2). Compared to only 12.8% in the general population, 35.3% of those with bipolar I disorder [odds ratio (OR) = 3.9] and 33.4% of those with bipolar II disorder (OR = 3.5) met criteria for nicotine dependence in the prior 12 months (2). Beyond the adverse health implications of smoking, bipolar patients who smoke are at higher risk of suicidal behavior and suicide attempts, independent of substance abuse and anxiety disorder comorbidity (3). Along with severity of depression and having made a prior suicide attempt, smoking was a robust predictor of suicidal behavior following a major depressive episode in bipolar disorder, even after controlling for other factors (4) and regardless of gender (5). Additionally, a study of adolescents with bipolar disorder found that cigarette smoking was independently associated with suicide attempts and substance use disorders (6, 7). It is unclear why smokers with bipolar disorder are more likely to make suicide attempts. Some have suggested that an aggression/impulsivity factor may predispose certain individuals with bipolar disorder to suicidal behavior, substance use disorders, and smoking (4, 8, 9). In a prospective study, hostility predicted suicide attempts in individuals with bipolar disorder, although the relationship between hostility and smoking was not examined (10). In this prospective, longitudinal study of suicidal ideation and behavior in a clinical sample of patients with bipolar disorder, we examined current cigarette smoking using a well-validated measure of suicidal ideation and behaviors at baseline and prospectively at nine-month follow-up, and employed a validated assessment of impulsivity. We hypothesized that smoking would be a significant predictor of suicidality at baseline and at nine-month follow-up.