Deterioration of true resting state electroencephalographic alpha rhythms in patients with mild cognitive impairment due to Alzheimer’s disease at a 6‐Month follow‐Up

Abstract

AbstractBackgroundPrevious studies have shown that patients with Mild Cognitive Impairment due to Alzheimer’s disease (ADMCI) were characterized by reduced posterior rsEEG alpha rhythms after a 12‐month follow‐up (Babiloni et al., 2013). However, none of them have found an alpha deterioration considering a shorter follow‐up.A promising neurophysiological biomarker of the quiet vigilance alteration is the measurement of the posterior rsEEG alpha rhythms reduction in amplitude (reactivity) in the transition from the eyes‐closed to the eyes‐open condition (Babiloni et al., 2022).Here we tested the exploratory hypothesis that ADMCI reactive patients may display a deterioration of rsEEG alpha rhythms at a 6‐month follow‐up as a sign of disease progression (a relevant feature for intervention clinical trials).MethodClinical, neuroimaging, and rsEEG datasets in 52 ADMCI and 60 matched healthy elderly (Healthy) seniors were available from an international archive (www.pdwaves.eu). The rsEEG frequency bands were individual delta, theta, and alpha (defined based on its posterior topography and “reactivity” to the eyes‐open condition) or background frequency (BGF), as well as fixed beta (14‐30 Hz) and gamma (30‐40 Hz). Cortical source estimation was performed by eLORETA freeware.ResultA substantial (> ‐10%) reduction in the posterior alpha source activities during the eyes‐open condition in about 90% and 70% of the Healthy and ADMCI participants, respectively. In the younger ADMCI participants (mean age of 64.3±1.1) with “reactive” rsEEG alpha source activities, posterior alpha source activities during the eyes‐closed condition predicted the global cognitive status at 6‐month follow‐up. In all younger ADMCI participants with “reactive” rsEEG alpha source activities, posterior alpha source activities during the eyes‐closed condition reduced in magnitude at that follow‐up. These effects could not be explained by neuroimaging and neuropsychological biomarkers of AD.ConclusionThese results suggest that in ADMCI patients, the true (“reactive”) posterior rsEEG alpha rhythms, when present, predict (in relation to younger age) and are quite sensitive to the effects of the disease progression on neurophysiological mechanisms underpinning vigilance regulation.