ABNORMALITIES OF ELECTROENCEPHALOGRAPHIC (EEG) MARKERS IN QUIET WAKEFULNESS ARE RELATED TO MOTOR DEFICITS, COGNITIVE SYMPTOMS, AND VISUAL HALLUCINATIONS IN PARKINSON’S DISEASE PATIENTS

Abstract

Parkinson's disease (PD) is the second-most common neurodegenerative disorder that affects 2–3% of the population ≥ 65 years of age. It is characterized by motor dysfunctions, but non-motor (i.e. cognitive and psychiatric) features contribute extensively to its presentation and disease burden. Here we tested the hypothesis that cortical sources of resting state eyes-closed electroencephalographic (rsEEG) rhythms may differ in PD patients as a function of motor symptoms, cognitive deficits, and visual hallucinations. Clinical and rsEEG rhythms in demographic matched PD (N = 93), Alzheimer's disease (AD, N= 70) and healthy elderly (Nold, N = 60) subjects were available from an international archive. Individual alpha frequency peak was used to determine the delta, theta, alpha1, alpha2, and alpha3 frequency band ranges. Fixed beta1, beta2, and gamma bands were considered. The eLORETA freeware estimated rsEEG cortical sources. As a confirmation of previous studies, compared to the Nold subjects, the AD and PD patients showed higher widespread delta source activities and lower posterior alpha source activities. Specifically, posterior alpha source activities were more abnormal in the AD than the PD group, while widespread delta source activities were more abnormal in the PD than the AD group. As novel results, (1) the PD patients with the most pronounced motor deficits exhibited very low alpha source activities in widespread cortical regions; (2) the PD patients with the strongest cognitive deficits showed higher delta and alpha source activities in widespread cortical regions; and (3) in relation to the PD patients without visual hallucinations, those with visual hallucinations were characterized by higher parieto-occipital alpha sources activities (Figure 1).