Attention deficit hyperactivity disorder: an update.

Attention deficit hyperactivity disorder (ADHD) is the most common neurobehavioral disorder, affecting 3% to 5% of school-aged children. Of the 3 subtypes--predominantly inattentive, predominantly hyperactive/impulsive, and a combined subtype--the latter is the most commonly represented group, accounting for 50% to 70% of all ADHD individuals. Stimulant medication is the cornerstone of management; however, stimulants with a short duration of action have been problematic for some patients. Recent technologic advances in delivery systems offer many patients the option of a once-daily dosage.