Reactivity of posterior cortical electroencephalographic alpha rythms during eyes opening in cognitively intact older adults and patients with dementia due to Alzheimer's and lewy diseases

Introduction: Patients with Lewy Bodies (DLB) and Parkinson’s disease dementia (PDD) suffer from vigilance dysregulation reflected by hypersomnolence, cognitive fluctuations, hallucinations, and sleep disorders. Therefore, we hypothesized that such dysregulation may be reflected by altered reactivity of posterior resting-state electroencephalographic (rsEEG) alpha rhythms during the vigilance transition from eyes-closed to -open condition. More specifically, we tested whether the above mentioned reactivity of posterior rsEEG alpha rhythms may differ in patients with DLB, PDD and Alzheimer’s disease (ADD) dementia, as a functional probe of the dominant cortical neural synchronization mechanisms regulating the vigilance in posterior visual systems. Methods: In two different studies, we extracted clinical, demographical, and rsEEG datasets in (1) older adults (Healthy, N=28) seniors as well as matched DLB (N=42) and ADD (N=48) patients, and (2) 25 Healthy seniors as well as matched PDD (N=73) and ADD (N=35) patients, from an international Eurasian database. The eLORETA freeware was used to estimate cortical rsEEG sources at delta, theta, alpha, beta, and gamma frequency bands during eye-closed and eye-open conditions.