Abnormalities of reactivity of posterior resting‐state electroencephalographic alpha rhythms during eyes opening in patients with dementia due to Alzheimer’s disease and Parkinson’s disease

Abstract

AbstractBackgroundPatients with dementia due to Alzheimer’s disease (ADD) and Parkinson’s disease (PDD) suffer from vigilance dysregulation. 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.MethodA Eurasian database provided clinical, demographic, and rsEEG datasets in 73 PDD patients, 35 ADD patients, and 25 matched cognitively unimpaired (Healthy) persons. The eLORETA freeware was used to estimate cortical rsEEG sources at delta, theta, alpha, beta, and gamma frequency bands during eyes‐closed and‐open conditions.ResultResults showed substantial (> ‐10%) reduction (reactivity) in the posterior alpha source activities from the eyes‐closed to the eyes‐open condition in 88% of the Healthy seniors, 57% of the ADD patients, and only 35% of the PDD patients (Figure 1). In these alpha‐reactive participants, there were lower reductions in the posterior alpha activities in the ADD and PDD groups than in the Healthy group. That reduction in the parietal region was lower in the PDD than in the ADD group (Figure 2).ConclusionThese results suggest that ADD and PDD is characterized by poor reactivity of mechanisms desynchronizing posterior rsEEG alpha rhythms in response to visual inputs. This finding could be an interesting biomarker of impaired vigilance regulation in the quiet wakefulness in ADD and PDD patients. Such biomarkers may provide endpoints targets for pharmacological intervention and brain electromagnetic stimulations to improve the ADD and PDD patients’ general ability to regulate vigilance and visual primary consciousness in the activities of daily living.