A resting-state alpha sub-band marker of attentional vulnerability in children with high-risk for ADHD: A preliminary electrophysiological study.

BACKGROUND: Electrophysiological biomarkers of Attention-Deficit/Hyperactivity Disorder (ADHD) have largely focused on the theta/beta ratio, reflecting cortical underarousal. Alpha-band activity also supports attentional regulation, yet functional differentiation of alpha sub-bands remains insufficiently characterized, particularly in symptomatically high-risk populations. This study assessed regional differences in the alpha1 (8-10 Hz)/alpha2 (10-12 Hz) (α1/α2) ratio during resting-state EEG in CSI-4 screen-positive children at high-risk for ADHD compared with typically developing controls. METHODS: EEG data were analyzed in 84 community children: a symptomatically high-risk group (CSI-4 screen-positive for ADHD, n = 42) and matched controls (n = 42). The α1/α2 power ratio was calculated across frontal, central, temporal, parietal, and occipital electrodes during eyes-open (EO) and eyes-closed (EC) conditions. RESULTS: No group differences appeared in EO. However, the high-risk group showed significantly higher α1/α2 ratios during EC (p < .001), in central, temporal, and parietal regions, indicating altered posterior-central network activity. Frontal and occipital regions showed no significant differences. DISCUSSION: Findings indicate a condition-specific increase in the α1/α2 ratio within dorsal attention and posterior visual networks as an electrophysiological signature of high-risk ADHD. These findings provide evidence for a condition-specific elevation of the α1/α2 ratio. Future longitudinal studies are needed to evaluate its utility.