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Attention deficit hyperactivity disorder (AD/HD) is a condition typically first evident in early childhood. Symptoms include deficits in attention, concentration, and short-term memory. Behaviorally, children with AD/HD are overly active (as if “driven by a motor”) and unable to remain seated, highly distractible, and impulsive. Concerns about AD/HD often initially arise during kindergarten or first grade, since these deficits significantly impair academic performance and are disruptive in a typical classroom. However, AD/HD is increasingly viewed as a lifelong condition with functional impairment extending throughout adulthood.

Recent data suggest a 6–8% prevalence rate. To date, the majority of epidemiologic studies have been conducted in North America and Europe. However, available data suggest that the condition has similar prevalence rates in Asia, Africa, and Latin America with a pooled worldwide rate of 5.3%. However, there is also considerable variability in prevalence rates that may reflect differing diagnostic practices, differing definitions of the condition, or both. A recent US study by the Centers for Disease Control reported state-based prevalence rates ranging from 5.6% (Nevada) to 15.6% (North Carolina). AD/HD disproportionately affects males with a sex ratio between 3:1 and 9:1, with more conservative figures in clinic rather than community samples. Lower socioeconomic status (SES) has been associated with increased AD/HD rates in international studies.

There are two essential clusters of AD/HD symptoms: inattention and hyperactivity/impulsivity. Symptoms of AD/HD include either inattention (failing to give attention to detail, problems maintaining attention, not appearing to listen when spoken to directly, failure to follow through on instructions and to complete schoolwork or other tasks, problems with organization, avoiding activities requiring sustained concentration, losing important items, being easily distracted, and forgetfulness), or hyperactivity/impulsivity (fidgeting, inability to remain seated, inappropriate running and climbing, difficulty playing quietly, acting as if “driven by a motor,” excessive talking, blurting out answers before questions are finished, difficulty taking turns, and intruding upon others’ activities and/or conversations), or of both clusters. Children must have at least six symptoms from either (or both) the inattention group of criteria and the hyperactivity and impulsivity criteria, whereas older adolescents and adults (over the age of 17 years) must present with five. Most symptoms should have been present before the age of 12 years.


Four-and-a-half year old Ronnie has been dismissed from three preschools during the past 9 months. Ronnie’s mother brings a teacher’s note chronicling Ronnie’s recent behavior:

  • 2/25 = “Ran out of classroom and was on his way out of the building before I stopped him.”

  • 2/28 = “Threw all of the students’ coats on the floor . . won’t listen when he’s told to hang them up.”

  • 3/2 = “Would not sit through story time. Threw milk cartons during lunch time.”

In your examination room, Ronnie is lying across your stool face down yelling, “I’m flying,” while pushing off from the walls with his feet. His mother, appearing exhausted, makes a ...

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