They are Dennis the Menace come to life, half-pint hellions who drive parents and teachers to distraction with their disruptive antics. At home they clamber on kitchen counters, unscrew light bulbs and mess up the simplest tasks, from hanging up their clothes to making the bed. In school they throw erasers, kick desks, shove classmates and are so busy making nuisances of themselves that they fail to absorb their lessons. One bedeviled mother speaks for many when she says, "I would have given the kid away."
Such hyperactivity has emerged within the past decade as the most common -- and controversial...