Attention-Deficit/Hyperactivity Disorder in Childhood and Adolescence and the Risk of Crime in Young Adulthood in a Danish Nationwide Study

Objective: To determine the risk of long-term conviction and incarceration associated with childhood attention-deficit/hyperactivity disorder (ADHD), and to identify risk and protective factors including associations with active treatment with ADHD medication. Method: All participants with ADHD who were 4 to 15 years of age during 1995 to 2005 were matched by year of birth and sex to a random sample of participants without ADHD from the Danish population using nationwide registers. Using Cox proportional hazard models, we estimated the risk of conviction and incarceration associated with ADHD in childhood and estimated associations with active treatment and outcome. Results: The ADHD cohort were followed up at a mean of 22.0 (SD = 5.8) years. Of 4,231 individuals with ADHD, 1,355 (32.0%) had received at least one conviction, compared to 3,059 (15.6%) of the 19,595 participants without ADHD (p < 0.001). ADHD was significantly associated with conviction (hazard ratio [HR] = 2.4, 95% CI = 2.3-2.6) and incarceration (HR = 3.0, 95% CI = 2.8-3.3). Subsequent to adjustment for various risk factors, ADHD exposure was still significantly related to conviction (HR = 1.6, 95% CI = 1.5-1.8) and incarceration (HR = 1.7, 95% CI = 1.5-1.9). Comorbidity with substance use disorder, oppositional-defiant disorder/conduct disorder, low family socioeconomic status, parental incarceration, and parental relationship status all significantly increased the risk of conviction and incarceration. Crime rates increased with the number of associated risks but were reduced during periods of taking ADHD medication. Conclusion: In addition to ADHD, a broad range of individual, familial, and social factors increase the risk of antisocial development. The findings imply that ADHD medication may contribute to crime prevention.