Abnormalities of Cortical Sources of Resting State Alpha Electroencephalographic Rhythms are Related to Education Attainment in Cognitively Unimpaired Seniors and Patients with Alzheimer’s Disease and Amnesic Mild Cognitive Impairment

Abstract

In normal old (Nold) and Alzheimer’s disease (AD) persons, a high cognitive reserve (CR) makes them more resistant and resilient to brain neuropathology and neurodegeneration. Here, we tested whether these effects may affect neurophysiological oscillatory mechanisms generating dominant resting state electroencephalographic (rsEEG) alpha rhythms in Nold and patients with mild cognitive impairment (MCI) due to AD (ADMCI). Data in 60 Nold and 70 ADMCI participants, stratified in higher (Edu+) and lower (Edu–) educational attainment subgroups, were available in an Italian–Turkish archive. The subgroups were matched for age, gender, and education. RsEEG cortical sources were estimated by eLORETA freeware. As compared to the Nold-Edu– subgroup, the Nold-Edu+ subgroup showed greater alpha source activations topographically widespread. On the contrary, in relation to the ADMCI-Edu– subgroup, the ADMCI-Edu+ subgroup displayed lower alpha source activations topographically widespread. Furthermore, the 2 ADMCI subgroups had matched cerebrospinal AD diagnostic biomarkers, brain gray–white matter measures, and neuropsychological scores. The current findings suggest that a high CR may be related to changes in rsEEG alpha rhythms in Nold and ADMCI persons. These changes may underlie neuroprotective effects in Nold seniors and subtend functional compensatory mechanisms unrelated to brain structure alterations in ADMCI patients.

Magnetoencephalography Brain Signatures Relate to Cognition and Cognitive Reserve in the Oldest-Old: The EMIF-AD 90 + Study

“…However, we have also shown that the relationship between cognitive reserve and spectral features is independent from memory and executive control performance, which was taken into account through the multivariate nature of our analyses and replication of results in the cognitively normal group. Yet, the spectral signature of cognitive reserve might change as a function of the pathological substrate underlying cognitive decline ( Babiloni et al, 2021 ). Considering the small size of the CI group, it was not possible to perform reliable correlation analyses within this group.…”

Measures of resting state EEG rhythms for clinical trials in Alzheimer's disease: Recommendations of an expert panel

“…In an ITALIAN‐TURKEY rsEEG study (Class A), compared to CU persons ( n = 60), ADMCI patients with high ( n = 35) and low ( n = 35) education attainments presented greater alpha source activations topographically widespread 53 . On the contrary, in relation to the ADMCI subgroup with low education attainment, the ADMCI subgroup with high education attainment displayed lower alpha source activations topographically widespread (notably, the two ADMCI subgroups had matched cerebrospinal AD diagnostic biomarkers, apolipoprotein E [ APOE ] ε4 genotyping, brain gray–white matter measures, and neuropsychological scores).…”

Robust EEG Based Biomarkers to Detect Alzheimer’s Disease

“…In quiet wakefulness, scalp rsEEG rhythms at posterior channels are dominated by alpha-band oscillations. These oscillations reflect the fluctuating cortical inhibition and the underlying widespread synchronization of cortical pyramidal neurons [186]. Indeed, studies have shown that neural signals synchronized at around 10 Hz subserve vigilance and attention [45,70,187,188].…”