We investigated whether adult attention-deficit/hyperactivity disorder (ADHD) predicts risky substance use and substance use disorders (SUDs), and its impact on the course of these problematic substance use patterns. Our sample included 4975 Swiss men (mean age 20 ± 1.2 years) who participated in the baseline and 15-month follow-up assessments of the Cohort Study on Substance Use Risk Factors. We examined: (1) the contribution of ADHD, as assessed at baseline, on the risky use of alcohol, nicotine and cannabis, and their corresponding use disorders (AUD, NUD, CUD) at follow-up; and (2) the association between ADHD and the course of outcomes (i.e., absence, initiation, maturing out, persistence) over 15 months. All analyses were adjusted for socio-demographics and co-morbidity. Men with ADHD were more likely to exhibit persistent risky alcohol and nicotine use, and to mature out of risky cannabis use. ADHD at baseline was positively linked to AUD and negatively to CUD at follow-up, but not to NUD. For all SUDs, ADHD had a positive association with use persistence and maturing out. Comparing these two trajectories revealed that early age of alcohol use initiation distinguished between persistence and maturing out of AUD, while the course of NUD and CUD was related to ADHD symptoms and SUD severity at baseline. Already in their early twenties, men with ADHD are especially likely to exhibit persistent problematic substance use patterns. Substance-specific prevention strategies, particularly implemented before early adulthood, may be crucial to reducing the development and persistence of pathological patterns in such individuals.
Keywords: Adult attention-deficit/hyperactivity disorder; Alcohol; Cannabis; Nicotine; Risky substance use; Substance use disorder.