Decreased Alpha Reactivity from Eyes-Closed to Eyes-Open in Non-Demented Older Adults with Alzheimer's Disease: A Combined EEG and [<SUP>18</SUP>F]florbetaben PET Study

초록

Background: The degree of alpha attenuation from eyes-closed (EC) to eyes-open (EO) has been suggested as a neural marker of cognitive health, and its disruption has been reported in patients with clinically defined Alzheimer's disease (AD) dementia. Objective: We tested if EC-to-EO alpha reactivity was related to cerebral amyloid-beta (A beta) deposition during the early stage of AD. Methods: Non-demented participants aged >= 55 years who visited the memory clinic between March 2018 and June 2019 (N= 143; 67.8% female; mean age +/- standard deviation, 74.0 +/- 7.6 years) were included in the analyses. Based on the [F-18]florbetaben positron emission tomography assessment, the participants were divided into A beta+ (N= 70) and A beta- (N= 73) groups. EEG was recorded during the 7 min EC condition followed by a 3 min EO phase, and a Fourier transform spectral analysis was performed. Results: A significant three-way interaction was detected among A beta positivity, eye condition, and the laterality factor on alpha-band power after adjusting for age, sex, educational years, global cognition, depression, medication use, and white matter hyperintensities on magnetic resonance imaging (F = 5.987, p = 0.016); EC-to-EO alpha reactivity in the left hemisphere was significantly reduced in A beta+ subjects without dementia compared with the others (F = 3.984, p = 0.048). Conclusion: Among mild cognitive impairment subjects, alpha reactivity additively contributed to predict cerebral A beta positivity beyond the clinical predictors, including vascular risks, impaired memory function, and apolipoprotein E epsilon 4. These findings support that EC-to-EO alpha reactivity acts as an early biomarker of cerebral A beta deposition and is a useful measurement for screening early-stage AD.

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