Attention Deficit Hyperactivity Disorder

A growing body of research indicates that there is a connection between attention deficit hyperactivity disorder (ADHD) and substance use disorders (SUD). Of adolescents and adults with with SUD, 30% to 50% and 15% to 25%, respectively, also have ADHD. Compared to individuals with SUD alone, adolescents and adults with ADHD and SUD have greater drug use severity, greater difficulty achieving abstinence, and higher rates of relapse.

The association between ADHD and SUD begs the question of whether treatment of ADHD in childhood lowers the risk of developing SUD. Numerous controlled studies have shown that psychostimulant treatment of ADHD improves school performance, psychosocial functioning, and associated behavior problems. More recent studies show that treatment of ADHD may reduce the risk of adolescent SUD by as much as half compared to children whose ADHD goes untreated.

Whereas the evidence supporting a linkage between ADHD and SUD has strengthened over the past decade, the reasons for the connection are more obscure. The data indicate that the incidence of SUD is highest in youth who have significant behavior problems with ADHD. Twenty-five percent to seventy-five percent of children and adolescents with ADHD also meet DSM-IV diagnostic criteria for oppositional defiant disorder or conduct disorder. Conduct disorder, characterized by a chronic pattern of antisocial behaviors that violate the rights of others, is the most common co-occurring disorder in adolescents with SUD (60%–80%), followed by ADHD (30%–50%). Longitudinal studies indicate that the combination of ADHD and conduct disorder imparts the highest risk of adolescent substance abuse as well as higher rates of school failure, risky behaviors (including motor vehicle accidents), and association with a deviant peer group.

In a 19-year longitudinal study conducted by the Mayo Clinic, researchers concluded that psychostimulant medication treatment for childhood ADHD conferred a protective effect (especially for boys) against SUD when the youths were 15 to 21 years of age compared to those whose ADHD went untreated. The findings held even for the subset of children with both ADHD and comorbid conduct disorder, which raises the risk of drug abuse even more than ADHD alone. All untreated children with both ADHD and conduct disorder developed SUD; treatment reduced the number by about half.

Numerous controlled trials support the safety and efficacy of psychostimulant medications—and more recently, nonstimulant (e.g., atomoxetine) medications—for ADHD in children and adolescents without SUD. Because individuals with active substance abuse have traditionally been excluded from medication trials, less is known about the safety, efficacy, or abuse liability of psychostimulants in individuals with both ADHD and SUD. Results from two controlled trials in adults and one trial in adolescents indicate that psychostimulant medication may be relatively safe and effective for ADHD even in individuals who have not yet achieved abstinence. Results also indicate that pharmacotherapy for ADHD alone has little to no impact on active drug use.

More research is needed with larger sample sizes to determine whether pharmacotherapy for ADHD improves treatment outcomes for SUD when treatment for both disorders is concurrent. One such study is currently under way in the National Institute on Drug Abuse Clinical Trials Network. The study is a randomized controlled trial of osmotic-release methylphenidate in adolescents with ADHD receiving concurrent cognitive behavioral therapy for SUD. The aims of the study are to evaluate the safety, efficacy, and abuse liability of the long-acting psychostimulant for ADHD as well as the impact of treating ADHD on drug use and substance treatment retention and outcomes.

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