Averaged Evoked Potential Predictors of Clinical Improvement in Hyperactive Children Treated with Methylphenidate: An Initial Study and Replication

In two experiments certain measures of the visual evoked potential (VEP) discriminated between hyperactive children who were subsequently judged by their pediatrician to have shown significant improvement (responders) with methylphenidate (Ritalin) as compared to children who showed a poor or marginal response to this drug. The principal findings were: 1) With Ritalin, EP variability increased when responders went from a task requiring active attention (ATT) to one requiring passive observing (PAS). In contrast, EP variability decreased in nonresponders when they went from ATT to PAS. 2) The amplitude of the M40‐P190 component in the ATT condition increased from placebo to Ritalin for the responders. It was suggested that the variability measure primarily reflects an abnormalizing effect of Ritalin on the nonresponder while the N140‐P190 component represents an apparent deficit in responders that is normalized by Ritalin.