Screened Attention Deficit/Hyperactivity Disorder as a Predictor of Substance Use Initiation and Escalation in Early Adulthood and the Role of Self-Reported Conduct Disorder and Sensation Seeking: A 5-Year Longitudinal Study with Young Adult Swiss Men

Background: Attention deficit/hyperactivity disorder (ADHD), conduct disorder (CD), and sensation seeking (SS) have been consistently related to a higher risk of substance use (SU) and substance use disorder (SUD). Objectives: To investigate the relationship between ADHD and prevalence rates in males at age 20 and age 25, the initiation of SU and SUD after age 20, and the escalation of SU from age 20 to age 25, and to explore the role of CD and SS in the relation of ADHD with SU and SUD initiation and escalation. Method: Data were obtained as part of the Cohort Study on Substance Use Risk Factors (C-SURF), which focused on young Swiss men aged 20 years at baseline and 25 years at follow-up. Results: Participants who screened positive for ADHD at baseline exhibited a higher rate of SU and SUD than participants who screened negative. The presence of ADHD symptoms at age 20 predicted initiation of all SU between age 20 and age 25, except for alcohol and smoking. After controlling for self-reported CD and SS, ADHD still predicted this late initiation of use of hallucinogens, meth-/amphetamines, and ecstasy/MDMA; non-medical use of ADHD medication and sedatives, and alcohol use disorder (AUD). No escalation of weekly drinking and smoking or annual cannabis use was observed from age 20 to age 25. Conclusion: Screened-positive ADHD is an independent predictor of late SU and AUD, along with self-reported CD and SS. From a public health perspective, identifying ADHD is not only important in childhood and adolescence but also in early adulthood to guide specific interventions to lower risks of drug use initiation and the development of AUD in early adulthood.