Further Evidence for Smoking and Substance Use Disorders in Youth With Bipolar Disorder and Comorbid Conduct Disorder

Abstract

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. 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. 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. 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.