Abnormal electroencephalographic rhythms from quiet wakefulness to light sleep in Alzheimer\u27s disease patients with mild cognitive impairment

\ua9 2025 International Federation of Clinical NeurophysiologyObjectives: Alzheimer\u27s disease patients with mild cognitive impairment (ADMCI) show abnormal resting-state eyes-closed electroencephalographic (rsEEG) alpha rhythms (8–12 Hz) and may suffer from daytime sleepiness. Our exploratory study tested the hypothesis that they may present characteristic EEG rhythms from quiet wakefulness to light sleep during diurnal recordings. Methods: Datasets of 34 ADMCI and 22 matched healthy elderly (Nold) subjects were obtained from international archives. EEG recordings lasted approximately 30 min. Transitions of EEG activity from quiet wakefulness (alpha-dominant) to light sleep (theta-dominant ripples) were scored according to Hori\u27s vigilance stages. Cortical source activities were computed using the eLORETA software. Results: ADMCI (t-ADMCI, N = 18) over Nold (t-Nold, N = 11) participants were characterized by greater frontal EEG delta source activities and a lesser reduction (reactivity) in the posterior alpha source activities from quiet wakefulness to ripples. Notably, EEG delta source activities during quiet wakefulness were also greater in the ADMCI group transitioning to light sleep as compared to patients without said vigilance reduction. Conclusions: These results suggest that ADMCI patients with a greater susceptibility to daytime sleepiness may show characteristic EEG delta and alpha rhythms in the transition from quiet vigilance to daytime sleep. Significance: Our study showed a derangement of EEG rhythms during the transition to sleep possibly specific to AD

Alzheimer's Disease with Epileptiform EEG Activity: Abnormal Cortical Sources of Resting State Delta Rhythms in Patients with Amnesic Mild Cognitive Impairment

Background: Patients with amnesic mild cognitive impairment due to Alzheimer's disease (ADMCI) typically show a "slowing" of cortical resting-state eyes-closed electroencephalographic (rsEEG) rhythms. Some of them also show subclinical, non-convulsive, and epileptiform EEG activity (EEA) with an unclear relationship with that "slowing." Objective: Here we tested the hypothesis that the "slowing" of rsEEG rhythms is related to EEA in ADMCI patients. Methods: Clinical and instrumental datasets in 62 ADMCI patients and 38 normal elderly (Nold) subjects were available in a national archive. No participant had received a clinical diagnosis of epilepsy. The eLORETA freeware estimated rsEEG cortical sources. The area under the receiver operating characteristic curve (AUROCC) indexed the accuracy of eLORETA solutions in the classification between ADMCI-EEA and ADMCI-noEEA individuals. Results: EEA was observed in 15% (N = 8) of the ADMCI patients. The ADMCI-EEA group showed: 1) more abnormal Aβ42 levels in the cerebrospinal fluid as compared to the ADMCI-noEEA group and 2) higher temporal and occipital delta (<4 Hz) rsEEG source activities as compared to the ADMCI-noEEA and Nold groups. Those source activities showed moderate accuracy (AUROCC = 0.70-0.75) in the discrimination between ADMCI-noEEA versus ADMCI-EEA individuals. Conclusion: It can be speculated that in ADMCI-EEA patients, AD-related amyloid neuropathology may be related to an over-excitation in neurophysiological low-frequency (delta) oscillatory mechanisms underpinning cortical arousal and quiet vigilance

Abnormal electroencephalographic rhythms from quiet wakefulness to light sleep in Alzheimer's disease patients with mild cognitive impairment

Objectives: Alzheimer's disease patients with mild cognitive impairment (ADMCI) show abnormal resting-state eyes-closed electroencephalographic (rsEEG) alpha rhythms (8–12 Hz) and may suffer from daytime sleepiness. Our exploratory study tested the hypothesis that they may present characteristic EEG rhythms from quiet wakefulness to light sleep during diurnal recordings. Methods: Datasets of 34 ADMCI and 22 matched healthy elderly (Nold) subjects were obtained from international archives. EEG recordings lasted approximately 30 min. Transitions of EEG activity from quiet wakefulness (alpha-dominant) to light sleep (theta-dominant ripples) were scored according to Hori's vigilance stages. Cortical source activities were computed using the eLORETA software. Results: ADMCI (t-ADMCI, N = 18) over Nold (t-Nold, N = 11) participants were characterized by greater frontal EEG delta source activities and a lesser reduction (reactivity) in the posterior alpha source activities from quiet wakefulness to ripples. Notably, EEG delta source activities during quiet wakefulness were also greater in the ADMCI group transitioning to light sleep as compared to patients without said vigilance reduction. Conclusions: These results suggest that ADMCI patients with a greater susceptibility to daytime sleepiness may show characteristic EEG delta and alpha rhythms in the transition from quiet vigilance to daytime sleep. Significance: Our study showed a derangement of EEG rhythms during the transition to sleep possibly specific to AD