Further evidence for smoking and substance use disorders in youth with bipolar disorder and comorbid conduct disorder

Objective: Bipolar disorder (BPD) is a highly morbid disorder increasingly recognized in adolescents. The aim of this study was to examine the relative risk for substance use disorders (SUDs; alcohol or drug abuse or dependence) and cigarette smoking in adolescents with BPD. Methods: We evaluated the relative risk for SUDs and cigarette smoking in a case-controlled, 5-year prospective follow-up of adolescents with (n = 105, mean ± SD baseline age = 13.6 ± 2.5 years) and without ("controls"; n = 98, baseline age = 13.7 ± 2.1 years) BPD. Seventy-three percent of subjects were retained at follow-up (BPD: n = 68; controls: n = 81; 73% reascertainment). Our main outcomes were assessed by blinded structured interviews for DSM-IV criteria. Results: Maturing adolescents with BPD, compared to controls, were more likely to endorse higher rates of SUD (49% vs 26%; hazard ratio [HR] = 2.0; 95% confidence interval (CI), 1.1?3.6; P = .02) and cigarette smoking (49% vs 17%; HR = 2.9; 95% CI, 1.4?6.1; P = .004), as well as earlier onset of SUD (14.9 ± 2.6 [SD] years vs 16.5 ± 1.6 [SD] years; t = 2.6; P = .01). Subjects with conduct disorder (CD) were more likely to have SUD and nicotine dependence than subjects with BPD alone or controls (all P values < .05). When we added conduct disorder to the model with socioeconomic status and parental SUD, all associations lost significance (all P values > .05). Subjects with the persistence of a BPD diagnosis were also more likely to endorse cigarette smoking and SUD in comparison to those who lost a BPD diagnosis or controls at follow-up. Conclusions: The results provide further evidence that adolescents with BPD, particularly those with comorbid CD, are significantly more likely to endorse cigarette smoking and SUDs when compared to their non?mood disordered peers. These findings indicate that youth with BPD should be carefully monitored for comorbid CD and the development of cigarette smoking and SUDs.