A naturalistic assessment of the motor activity of hyperactive boys. II. Stimulant drug effects.

Twenty-four-hour motor activity was assessed in a naturalistic setting in 12 hyperactive boys for four weeks (672 consecutive hours). Dextroamphetamine, 15 mg/day, or placebo was administered on alternate weeks, using a double-blind ABAB design. When the boys received dextroamphetamine, motor activity was significantly decreased for about eight hours after drug administration. This decrease was followed by a period of slight but significant increases in activity ("rebound"). Dextroamphetamine decreased activity most strikingly during structured classroom activity; during physical education, however, there was a significant drug-induced increase in motor activity.