Association between Excessive Daytime Sleepiness and the Cholinergic Ascending Reticular System in Parkinson’s Disease

Abstract

<b><i>Background:</i></b> Excessive daytime sleepiness (EDS) in Parkinson’s disease (PD) may occur because of dysfunction on the brain areas in controlling wakefulness; however, the pathophysiology of EDS in PD has not been completely clarified. The Pb component of a middle-latency auditory evoked response (MLR) is generated from the cholinergic ascending reticular activating system (ARAS) projecting to the auditory cortex via the thalamus. We examined the association between EDS and the Pb component in patients with PD. <b><i>Methods:</i></b> Participants were 38 patients with nondemented PD and 18 age-matched controls. EDS was evaluated using the Japanese version of the Epworth Sleepiness Scale (JESS). PD patients were classified into the high sleepiness (HS) group and the low sleepiness (LS) group by the score of JESS. MLRs were recorded from the scalp with each earlobe as a reference under presentation of 1-Hz and 65- to 90-dB click sounds. <b><i>Results:</i></b> There was no difference in age, duration, and motor function between the HS PD and the LS PD groups. Peak latencies of Pb were not different between PD group and controls; however, Pb amplitudes were significantly increased in the HS PD group compared with the LS PD group and controls. <b><i>Conclusion:</i></b> One of the mechanisms of EDS in PD was suggested to be dysregulation of cholinergic neurons from the ARAS projecting to cortical cholinergic neurons.

Two-week Computerized Cognitive Training Affects Resting-State Electroencephalographic Rhythms in Parkinson’s Disease Patients with Cognitive Deficits

“…Although the assessment of PDCD patients is typically focused on motor and cognitive deficits, they often suffer from dysregulations of quiet vigilance (e.g., mental fatigue, cognitive fluctuations, etc.) and diurnal sleepiness, possibly due to impairments in subcortical ascending arousing systems [22][23][24][25][26]. The abnormal neurophysiological mechanisms underpinning those dysregulations can be investigated by the analysis of eyes-closed resting-state electroencephalographic (rsEEG) rhythms recorded from the scalp in quiet wakefulness (for a recent review, see [27]).…”