Methylphenidate in Hyperkinetic Children: Differences in Dose Effects on Impulsive Behavior

This research tested the hypothesis that in hyperactive children a low dose of methylphenidate (0.3 mg/kg) would produce scores superior to those with a high dose (1.0 mg/kg) or placebo on the matching familiar figures test (MFF), a primary index of impulsivity. The hypothesis was based on an earlier finding that the highest percentage of correct responses on a short-term memory task were found in hyperactive subjects who were receiving 0.3 mg/kg of methylphenidate whereas at 1.0 mg/kg the percentage correct returned to the placebo level. The hypothesis was verified in that the low dose reduced the number of errors on the MFF significantly more than did placebo or the high dose. This work demonstrates that, for both learning and impulsivity in hyperactive children, the lower dose of the two doses of methylphenidate studied produced the preferable effect.