A Dose‐Response and Time‐Action Analysis of Autonomic and Behavioral Effects of Methylphenidate in Attention Deficit Disorder with Hyperactivity

Abstract

Empirical attempts to correlate behavioral and physiological responses of hyperactive children to methylphenidate treatment have been complicated by methodological issues, including the demonstrated heterogeneity in the pool of hyperactive children, and the need to consider both dose‐response and timeaction parameters of drug action. Ten hyperactive children, selected according to objective behavioral criteria, were each assessed in 3 placebo days and 3 drug treatment days varying in methylphenidate dosage. Heart rate, finger temperature, electrodermal variables, gross motor activity, serial reaction time (as a measure of attention), and impulsive errors of commission were measured before and at varying intervals following drug or placebo administration. Time‐action curves of methylphenidate's effects on reaction time and on activity were dissimilar, with changes in reaction time more closely paralleling changes in the cardiovascular variables. These findings suggested that attentional deficit and inadequate motor inhibition represent divergent behavioral manifestations of hyperactivity, possibly corresponding to divergent neurophysiological substrates.