Exploration of electroencephalogram response to MPH treatment in ADHD patients

•EEG patterns of ADHD patients and healthy subjects were significantly different on several EEG indices, including the theta/beta ratio.•EEG dynamics before and after 8 ± 2 weeks of MPH treatment were not significantly different despite the remission of ADHD symptoms, due to their heterogeneity.•After MPH treatment, MPH good and poor responders had different EEG patterns, and some EEG features were normalized by MPH treatment only in MPH good responders. Our study demonstrates the possibility of these EEG indices as prognostic markers for ADHD therapeutic efficacy. Attention-deficit/hyperactivity disorder (ADHD) is known to be associated with several diagnostic resting-state electroencephalography (EEG) patterns, including the theta/beta ratio, but no objective predictive markers for each medication. In this study, we explored EEG markers with which the therapeutic efficacy of medications could be estimated at the 1st clinical visit. Thirty-two ADHD patients and thirty-one healthy subjects participated in this study. EEG was recorded during eyes-closed resting conditions, and ADHD symptoms were scored before and after the therapeutic intervention (8 ± 2 weeks). Although comparing EEG patterns between ADHD patients and healthy subjects showed significant differences, EEG dynamics, e.g., theta/beta ratio, in ADHD patients before and after MPH treatment were not significantly different despite improvements in ADHD symptoms. We demonstrated that MPH good responders and poor responders, defined by the efficacy of MPH, had significantly different theta band power in right temporal areas, alpha in left occipital and frontal areas, and beta in left frontal areas. Moreover, we showed that MPH good responders had significant improvements toward normalization in several coherence measures after MPH treatment. Our study implies the possibility of these EEG indices as predictive markers for ADHD therapeutic efficacy.