An association between attention-deficit/hyperactivity disorder (ADHD) and alcohol or drug abuse is well documented. Dr. Wilens noted that onset of ADHD typically occurs before age 7 years and affects 5% of children worldwide. In approximately 50% of these children, the disorder persists into adulthood, and is therefore considered a long-term chronic condition. Substance use disorders usually begin in adolescence or early adulthood and affect 10 to 30% of US adults. A substantial but less well defined rate of substance use disorders occurs among children and adolescents.

Using tobacco smoking as an example of a substance use disorder, Dr. Wilens described a study of adolescent smoking. When he and his colleagues separately considered adolescent smokers who had or did not have ADHD, they found that nine percent of those without ADHD reported smoking, compared with 16 percent of those with ADHD. A relationship between tobacco smoking and ADHD may persist into adulthood.

People with ADHD who are untreated or non-compliant with treatment have high risk for comorbid psychiatric disorders such as substance use disorder, depression, and anxiety disorders. ADHD is undertreated: current estimates suggest that fewer than 5 percent of children with ADHD receive treatment.

In contrast, patients whose symptoms of ADHD are controlled by pharmacotherapy have a usual life-course. Five studies have reported reduced rates of substance abuse in patients treated for ADHD. Dr. Wilens believes that pharmacotherapy may protect patients with ADHD from developing substance use disorders. Further study of medication-related protective effects may lead to development of more specifically targeted treatments for patients with ADHD. More refined treatments may decrease morbidity and improve long-term outcome in adolescents and adults with comorbid substance abuse.