Event-related wave activity in the EEG provides new marker of ADHD

ObjectiveThis study examines the utility of new measures of event-related spatio-temporal waves in the EEG as a marker of ADHD, previously shown to be closely related to the P3 ERP in an adult sample.MethodsWave activity in the EEG was assessed during both an auditory Oddball and a visual continuous performance task (CPT) for an ADHD group ranging in age from 6 to 18 years and comprising mostly Combined and Inattentive subtypes, and for an age and gender matched control group.ResultsThe ADHD subjects had less wave activity at low frequencies (∼1 Hz) during both tasks. For auditory Oddball targets, this effect was shown to be related to smaller P3 ERP amplitudes. During CPT, the ∼1 Hz wave activity in the ADHD subjects was inversely related to clinical and behavioral measures of hyperactivity and impulsivity. CPT wave activity at ∼1 Hz was seen to “normalise” following treatment with stimulant medication.ConclusionsThe results identify a deficit in low frequency wave activity as a new marker for ADHD associated with levels of hyperactivity and impulsivity.SignificanceThe marker is evident across a range of tasks and may be specific to ADHD. While lower ∼1 Hz activity partly accounts for reduced P3 ERPs in ADHD, the effect also arises for tasks that do not elicit a P3. Deficits in behavioral inhibition are hypothesized to arise from underlying dysregulation of cortical inhibition.