Event-related potentials in children with attention-deficit/hyperactivity disorder and excess beta activity in the EEG
This study investigated whether ERPs from an inter-modal oddballtask could distinguish between two groups of children withAttention-Deficit/Hyperactivity Disorder (AD/HD) of the combinedtype, with and without excess beta in their EEG, and controls.Three age-matched groups of male children (20 typical AD/HDwithout excess beta, 20 AD/HD with excess beta, 20 controls)were presented with an inter-modal oddball task in whicha counter-phasing checkerboard was the non-target visual sti -mulus (randomly presented on 80% of trials), and a 2000 Hztone was the auditory target (20% of trials). Stimuli were presentedat a fixed rate (stimulus-onset asynchrony 1.03 s) andparticipants were required to silently count all targets.Compared with controls, the AD/HD group without excess betashowed reduced P2 and P3 to auditory targets, topographic differencesin target N1 and N2, and reduced P2 and P3 to visualnon-targets, replicating previous AD/HD research. The AD/HDgroup with excess beta showed a general reversal of theseeffects in the auditory target N1, P2, N2, and P3, and visualnon-target N1, P2 and P3, appearing similar to the controlgroup. However, their visual non-target P1 was more aberrantthan that of the other AD/HD group.These results suggest that the children with excess beta do notdemonstrate the impaired discrimination and categorizationusually noted in children with AD/HD of the combined type.Further research on the cognitive and perceptual functioning ofEEG-defined subgroups of AD/HD is warranted.