Mismatch negativity in hyperactive children: effects of methylphenidate.

This pilot study investigates electrophysiological correlates of methylphenidate (MP) treatment among hyperkinetic children who are clinical responders to therapy. Event-related potentials were obtained from a small sample (6 hyperactive and 5 controls) during an auditory "oddball" task. In the ignore condition, oddball tones elicited a frontocentral "mismatch" negativity (MMN) during the 100- to 200-msec latency range following stimulus presentation. In the attend condition, oddball target tones elicited a centroparietal P3 as well. MP significantly decreased hyperkinetic behaviors. Preliminary analyses of the electrophysiological data indicated a decreased amplitude of the P3 waveform among hyperkinetic children and a trend toward normalization on MP. Waveform abnormalities in the latency range of control MMN suggested either a decrease in MMN amplitude or an increase in MMN latency in hyperactive subjects along with a trend toward normalization by MP. The preliminary data are suggestive of information-processing abnormalities among hyperactive children that may be sensitive to MP therapy.