Dexamphetamine normalises electrophysiological activity in attention deficit-hyperactivity disorder during the Stroop task.

A case study was conducted to investigate whether dexamphetamine enhances interference control in an adult with attention deficit/hyperactivity disorder. Continuous electroencephalography was recorded both on and off dexamphetamine during performance on a Stroop task. An age-, gender- and IQ-matched control also completed the same task. Event related potentials for the control participant revealed a positive potential to incongruent stimuli between 270 and 440 ms, whereas for the participant with attention deficit/hyperactivity disorder off medication, the reverse polarity was observed in a later time window. Following administration of dexamphetamine, however, the event-related potentials for the incongruent condition closely resembled those in the control, suggesting that dexamphetamine successfully normalises electroencephalographic activity.