Attention-deficit/hyperactivity disorder (ADHD) is a genetic disorder that affects both children and adults. Genetic studies have shown the heritability of ADHD to be higher than other psychiatric disorders. In addition, imaging studies have revealed various structural anomalies in the brain.

Often ADHD persists into adulthood. The presentation of ADHD into adulthood most often results from childhood onset of ADHD. Symptoms of inattention and functional behavior tend to persist. These symptoms may often be less obvious, with less overt hyperactivity and impulsiveness.

Stimulant medications remain the predominant choice for the treatment of ADHD. They are safe and offer good response. Common adverse reactions can usually be removed by changing the dose and the timing of medication administration. Of the second-line agents for treating ADHD, the tricyclic antidepressants have generated the most studies and have proved fairly efficacious.