The challenge of predicting which children with attention deficit-hyperactivity disorder will respond positively to methylphenidate

Predicting which children with Attention Deficit-Hyperactivity Disorder (ADHD) will respond to methylphenidate (MPH; Ritalin) is of theoretical interest, for example, for understanding catecholamine contributions to self-regulation. Large individual differences in response to MPH and the wide prescription of MPH for ADHD have encouraged research on response prediction. We reviewed 59 studies conducted since the last major review by Barkley in 1976 and examined responder definition, comorbidities, demographics, intelligence, inhibitory control, physiological measures, and placebo response. Strong responders are more easily predicted; children with anxiety, who are older, or have less severe symptoms do not respond as well. Measures of inhibitory control and catecholamines are weakly associated. Prediction on a case-by-case basis is not possible, and group findings have not generalized well. Implications of these findings for the validity of the disorder are discussed.