Preschool attention deficit hyperactivity disorder: a review of prevalence, diagnosis, neurobiology, and stimulant treatment.

The clinical use of stimulant medications for 3- to 6-year-old preschool children who meet diagnostic criteria for attention deficit hyperactivity disorder (ADHD) is becoming more common. A systematic computerized literature search extending back to 1970 identified nine controlled studies of stimulant treatment and two controlled trials of stimulant side effects in preschool ADHD children. Treatment benefits are reported for eight of nine (89%) controlled stimulant trials involving a total of 206 preschool subjects. In comparison with school-aged ADHD youth, there may be a greater variability of stimulant response in ADHD preschoolers. Domains assessing cognition, interpersonal interactions, and hyperactive-impulsive behavior are noted to improve on drugs relative to placebos. Side effects in this age range are generally reported as mild. ADHD preschool children may experience slightly more and different types of stimulant-induced side effects compared with older children. High rates of behavior reported as stimulant side effects are found for children receiving a placebo, necessitating a baseline evaluation for medication side effects before stimulants are initiated. Despite the lack of research assessing stimulant effects on the very young and developing brain and the need for more controlled medication trials in this age range, this review of the extant literature finds stimulants to meet evidence based criteria as beneficial and safe for carefully diagnosed ADHD preschool children aged 3 years and older.