Sensitivity and specificity of EEG biomarkers of AD at the preclinical stage: Biomarkers (non‐neuroimaging) / novel biomarkers.

Background: Cognitive reserve (CR) is present in Alzheimer's disease (AD) seniors with high education attainment making them clinically resilient to extended brain neuropathology and neurodegeneration. Here we tested whether subjective memory complaint (SMC) seniors with AD neuropathology and high education attainment may present abnormal eyes‐closed resting state posterior electroencephalographic (rsEEG) rhythms around individual alpha frequency peak (IAFp), typically altered in AD patients with mild cognitive impairment and dementia. Method: We selected all individual baseline data of the prospective INSIGHT‐preAD cohort (Paris) including mini mental state examination score ≥ 28, artifact‐free markers of 18F‐florbetapir positron emission tomography (amyPET), structural magnetic resonance imaging, and rsEEG rhythms (e.g., 172 SMC seniors). Delta, theta, alpha1, alpha2, and alpha3 bands were determined on individual basis based on IAFp, while beta1 (14‐20 Hz), beta2 (20‐30 Hz), and gamma (30‐40 Hz) were standard fixed bands. Result: The SMC participants negative to amyPET AD markers (SMCneg) with high (over low‐moderate) education level showed higher posterior alpha 2 power density (possibly "neuroprotective"). Furthermore, amyPET‐positive SMC (SMCpos) participants with high (over low‐moderate) education level showed higher temporal alpha 3 power density (possibly "neuroprotective") and lower posterior alpha 2 power density (possibly "compensatory"; Figure 1). This effect may reflect CR as no differences in brain gray‐white matter and cognitive functions were observed between these SMCpos/SMCneg sub‐groups. Conclusion: Preclinical Alzheimer's neuropathology may interact with education attainment and neurophysiological mechanisms generating cortical alpha rhythms around IAFp (i.e., alpha 2 and 3) in quiet wakefulness. [ABSTRACT FROM AUTHOR]