Longitudinal Stability of Cognitive Reserve in Education and Preclinical Amyloidosis Among Seniors: A Resting-State EEG Study

In older adults with subjective memory complaints (SMC), education, as a proxy for cognitive reserve (CR), may exert neuroprotective or compensatory effects on brain function, as measured by resting-state electroencephalographic (rsEEG) alpha rhythms, depending on the presence of early Alzheimer's disease (AD) amyloid pathology. This experimental study investigated whether these effects remain stable over 24 months, focusing on rsEEG alpha rhythms in older adults with SMC, stratified by brain amyloid status (SMCpos vs. SMCneg) and educational attainment (Edu- vs. Edu+). The study included 84 older adults with SMC from the INSIGHT-preAD cohort. Participants were examined using rsEEG alpha power density over three time points (baseline, 12 months, 24 months). The results showed that SMCneg Edu+ participants exhibited higher posterior alpha rhythms compared to SMCneg Edu− participants, consistent with neuroprotective effects of CR. In contrast, SMCpos Edu+ participants showed lower posterior alpha rhythms relative to SMCneg Edu+, suggesting compensatory neural activity despite amyloid pathology. No significant changes in rsEEG alpha rhythms were observed over time, indicating longitudinal stability of these patterns across two years. These findings support the role of CR in modulating neurophysiological markers in preclinical AD and highlight the potential of rsEEG alpha rhythms as non-invasive biomarkers for early neural changes associated with AD.