In March of 1902 Dr. George Still stood before the Royal College of Physicians, in London, and described some children he had observed—mostly boys—who seemed to him restless, passionate, and apt to get into trouble. The children were suffering, he declared, from "an abnormal defect of moral control."
Despite his invocation of morality, Still's lecture is often billed as the first recorded discussion of hyperactivity. Thousands of articles on the subject have been published in professional journals since then, the great majority of them within the past two decades. A good proportion of these papers begin by citing the pervasiveness of the disorder. An opening sentence such as "Hyperactivity is the single most prevalent childhood behavioral problem" is usually regarded as sufficient, because the readers of these journals are already convinced that, on average, at least one hyperactive child sits in every elementary school classroom in the United States.
The actual estimates vary, however, and not by a little. If a psychiatrist says that about three percent or 10 percent or between one and five percent of elementary school children are hyperactive, this is simply a rough average of studies whose findings differ dramatically. One series of papers estimated the rate of hyperactivity at 10 to 20 percent. A California survey put it at precisely 1.19 percent. A nationally recognized expert says without hesitation that it is six percent. The one thing researchers generally agree on is that among children labeled hyperactive, boys outnumber girls by at least four to one.