Effects of stimulant medications on children with attention-deficit/hyperactivity disorder and excessive beta activity in their EEG

Objective: This study investigated the effects of stimulant medications on the Electroencephalography (EEG) of children with the combined type of attention-deficit/hyperactivity disorder (ADHD) together with excessive beta activity in their EEG. Methods: Twenty ADHD and 20 control subjects participated in this study. EEG was recorded from 21 sites during an eyes-closed resting condition and Fourier transformed to provide estimates for total power and absolute and relative power in the delta, theta, alpha and beta bands, and for the theta/alpha and theta/beta ratios. Subjects were placed on a 6-month trial of a stimulant medication and a second EEG was recorded at the end of the trial. Results: The unmedicated ADHD group had greater absolute and relative beta, less absolute and relative alpha, a higher theta/alpha and a lower theta/beta ratio than the control group. In the frontal regions the ADHD group had an increase in total power, absolute theta, absolute and relative beta and the theta/beta ratio, with greater relative delta, relative theta, and absolute and relative alpha in posterior regions. With medication use, absolute beta activity and frontal total power decreased, although these changes represented a reduction in power, not a normalisation. Conclusions: These results indicate that ADHD children with excessive beta activity in their EEG are probably not hypoaroused as previously suggested, and that beta activity in these children is probably only associated with the impulsivity and/or hyperactivity aspects of the disorder, but may not necessarily be associated with inattention. Significance: This study is the first to investigate effects of stimulant medications on the EEG of ADHD children with excessive beta activity in their EEG.