Excessive Daytime Sleepiness Predicts Neurodegeneration in Idiopathic REM Sleep Behavior Disorder.
To determine the association of excessive daytime sleepiness (EDS) with the conversion of neurodegenerative diseases in patients with idiopathic REM sleep behavior disorder (iRBD).



A total of 179 patients with iRBD (79.1% males, mean age = 66.3 ± 9.8 years) were consecutively recruited. Forty-five patients with Epworth Sleepiness Scale score ≥14 were defined as having EDS. Demographic, clinical, and polysomnographic data were compared between iRBD patients with and without EDS. The risk of developing neurodegenerative diseases was examined using Cox proportional hazards model.



After a mean follow-up of 5.8 years (SD = 4.3 years), 50 (27.9%) patients developed neurodegenerative diseases. There was a significantly higher proportion of conversion in patients with EDS compared to those without EDS (42.2 % vs. 23.1%, p = .01). EDS significantly predicted an increased risk of developing neurodegenerative diseases (adjusted hazard ratios [HR] = 2.56, 95% confidence interval [CI] 1.37 to 4.77) after adjusting for age, sex, body mass index, current depression, obstructive sleep apnea, and periodic limb movements during sleep. Further analyses demonstrated that EDS predicted the conversion of Parkinson's disease (PD) (adjusted HR = 3.55, 95% CI 1.59 to 7.89) but not dementia (adjusted HR = 1.48, 95% CI 0.44 to 4.97).



EDS is associated with an increased risk of developing neurodegenerative diseases, especially PD, in patients with iRBD. Our findings suggest that EDS is a potential clinical biomarker of α-synucleinopathies in iRBD.
Department of Psychiatry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.|Sleep Medicine Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
Junying
J
Zhou
Department of Psychiatry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.
Jihui
J
Zhang
Department of Psychiatry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.
Siu Ping
SP
Lam
Department of Psychiatry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.
Joey Wy
JW
Chan
Department of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.
Vincent
V
Mok
Department of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.
Anne
A
Chan
Sleep Research Clinic and Laboratory, Department of Psychology, The University of Hong Kong, Pokfulam Road, Hong Kong SAR.|The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR.
Shirley Xin
SX
Li
Department of Psychiatry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.
Yaping
Y
Liu
Sleep Medicine Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
Xiangdong
X
Tang
School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.
Wing Ho
WH
Yung
Department of Psychiatry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.
Yun Kwok
YK
Wing
D017668:Age of Onset; D000368:Aged; D015331:Cohort Studies; D003704:Dementia / Q000453:epidemiology / Q000503:physiopathology; D006970:Disorders of Excessive Somnolence / Q000453:epidemiology* / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000453:epidemiology* / Q000503:physiopathology; D010300:Parkinson Disease / Q000453:epidemiology / Q000503:physiopathology; D011379:Prognosis; D016016:Proportional Hazards Models; D020187:REM Sleep Behavior Disorder / Q000453:epidemiology* / Q000503:physiopathology; D012306:Risk; D012894:Sleep Stages / Q000502:physiology*; D051843:Synucleins / Q000378:metabolism
D051843:Synucleins
Parkinson’s disease; REM sleep behavior disorder; dementia.; excessive daytime sleepiness; neurodegenerative disease