Objective: This exploratory, hypothesis-generating study investigated alpha-band EEG activity during resting state and cognitive task performance in adults with Attention-Deficit/Hyperactivity Disorder (ADHD) and examined its relationship with symptom severity, without a healthy control group.
Method: EEG (8-12 Hz) was recorded in 28 adults with ADHD (21-31 years) during (1) eyes-closed rest and (2) a cognitive task requiring sustained attention. Absolute power and NeuroGuide z-scores were extracted. ADHD symptoms were assessed using the ASRS. Paired t-tests, Pearson correlations, and exploratory median split comparisons were performed.
Results: Resting and task alpha activity were strongly correlated (r = 0.77, p < 0.01). At the group level, alpha activity unexpectedly increased from rest to task (t(27) = 2.34, p = 0.027). Linear correlations between ASRS total score and alpha activity at rest (r = 0.07) and during task (r = 0.20) were weak and non-significant (p > 0.05). In exploratory median-split comparisons (higher vs. lower symptom severity), individuals with higher severity showed significantly lower task-related alpha (t(26) = 2.12, p = 0.044, d = 0.81), but no significant difference in resting alpha (t(26) = 1.92, p = 0.066).
Conclusions: In this hypothesis-generating study of adults with ADHD conducted without a neurotypical control group, we observed within-sample patterns of alpha modulation. The unexpected task-related alpha increase and the association between higher symptom severity and reduced task-related alpha warrant replication in larger, controlled studies with concurrent behavioral performance measures. No ADHD-specific conclusions can be drawn from this exploratory investigation.