Cigarette smoking as a risk factor for other substance misuse: 10-Year study of individuals with and without attention-deficit hyperactivity disorder

Background: We previously documented that cigarette smoking is a risk factor for subsequent alcohol and drug misuse and dependence in adolescent girls with attention-deficit hyperactivity disorder (ADHD). Aims: To revisit this hypothesis with a large longitudinal sample of both genders followed up for 10 years into young adulthood. Method: We used data from two identically designed, longitudinal, case-control family studies of boys and girls with and without ADHD ascertained from psychiatric and paediatric sources. We studied 165 individuals with ADHD and 374 controls followed up longitudinally and masked for 10 years. We assessed ADHD, smoking and substance use status using structured diagnostic interviews. We tested the association between cigarette smoking and subsequent substance use outcomes using Cox proportional hazard regression models. Results: Youth with ADHD who smoked cigarettes (n = 27) were significantly more likely to subsequently develop drug misuse and dependence compared with youth with ADHD who did not smoke (n = 138, P<0.05). Conclusions: These results confirm that cigarette smoking increases the risk for subsequent drug and alcohol use disorders among individuals with ADHD. These findings have important public health implications, and underscore the already pressing need to prevent smoking in children with ADHD.