Forty years of methylphenidate treatment in Attention-Deficit/ Hyperactivity Disorder.

This paper reviews approximately 40 years of stimulant drug treatment of children with behavior and learning problems. These patients generally fall under the rubric of Attention-Deficit/Hyperactivity Disorder (ADHD), with core symptoms of hyperactivity, impulsivity, and inattention being the most studied and most robust of the targets for stimulant treatment. In addition, the drug effects on other targets, such as cognitive and academic function, are included. The largest selection of studies involves methylphenidate. Both qualitative studies and meta-analytic studies from major reviews are examined. Variations in the methodology of the reviews are described and some of the discrepancies in interpretation examined. Despite wide variations in subject selection, types of trials, degree of methodological rigor, and the decade in which the studies took place, the evidence is remarkably consistent The overall results suggest significant clinical impact upon the core features of ADHD. More studies of long-term effects and special populations such as older adolescents and adults will be necessary, though existing evidence strongly supports similar findings as for the younger patients with a diagnosis of ADHD.