Application of resting-state EEG theta /alpha power ratio analysis for diagnosing amnestic mild cognitive impairment

This study aimed to investigate spectral power and the theta/alpha power ratio of resting-state electroencephalography (EEG) in patients with amyloid-positive amnestic mild cognitive impairment (aMCI) compared to normal controls (NC). Twenty-four patients with aMCI, confirmed by Pittsburgh Compound B positron emission tomography (PiB-PET), and twenty-four age-matched NC participants were included. Resting-state EEG recordings were analyzed for spectral power across delta, theta, alpha, and beta bands. Group comparisons and receiver operating characteristic (ROC) curve analyses, corrected for multiple comparisons using false discovery rate (FDR), were performed to assess diagnostic utility. Compared to NC, patients with aMCI exhibited EEG slowing, characterized by higher power in lower frequency bands and lower power in higher frequency bands. Regional analysis showed that the theta/alpha power ratio in the occipital region provided the best discrimination between groups (area under the curve [AUC] = 0.86), with high sensitivity and specificity (both > 91.7%). These findings indicate that patients with biomarker-confirmed aMCI present distinct, widespread electrophysiological alterations, possibly reflecting underlying neuropathological changes such as cholinergic dysfunction. This study provides a regional, quantitative evaluation of EEG spectral measures and their diagnostic performance in a PiB-PET-characterized aMCI cohort, offering exploratory evidence for the theta/alpha ratio as a potential adjunctive biomarker. Further validation in larger, independent samples is warranted.