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Research paper
Excessive daytime sleepiness in Chinese patients with sporadic amyotrophic lateral sclerosis and its association with cognitive and behavioural impairments
  1. Shuangwu Liu1,
  2. Yan Huang1,
  3. Hongfei Tai1,
  4. Kang Zhang1,
  5. Zhili Wang1,
  6. Dongchao Shen1,
  7. Hanhui Fu1,
  8. Ning Su1,
  9. Jiayu Shi1,
  10. Qingyun Ding1,
  11. Mingsheng Liu1,
  12. Yuzhou Guan1,
  13. Jing Gao1,
  14. Liying Cui1,2
  1. 1 Department of Neurology, Peking Union Medical College Hospital, Beijing, China
  2. 2 Neuroscience Center, Chinese Academy of Medical Sciences, Beijing, China
  1. Correspondence to Professor Liying Cui, Peking Union Medical College Hospital, Beijing 100730, China; pumchcuily{at}


Objective To examine the frequency and clinical features of excessive daytime sleepiness (EDS) and its association with cognitive and behavioural impairments in patients with amyotrophic lateral sclerosis (ALS).

Methods We conducted a cross-sectional investigation to explore the frequency and clinical features of EDS in a group of 121 Chinese patients with ALS compared with 121 age-matched and sex-matched healthy subjects. EDS was diagnosed using the Epworth Sleepiness Scale (ESS). Other characteristics of patients with ALS including sleep quality, REM sleep behaviour disorder (RBD), restless legs syndrome (RLS), cognition, behaviour, depression and anxiety were also evaluated.

Results EDS was significantly more frequent in patients with ALS than in controls (26.4% vs 8.3%; p<0.05). Patients with ALS with EDS scored lower scores on the revised ALS Functional Rating Scale (ALSFRS-R), Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA) and MMSE and MoCA delayed memory subitems and higher on the Frontal Behavioural Inventory (FBI) than patients with ALS without EDS. ESS scores correlated with global ALSFRS-R, FBI, MMSE and MoCA scores and MMSE and MoCA delayed memory scores. RLS and global ALSFRS-R scores were independently associated with EDS in patients with ALS.

Conclusions We identified a high frequency of EDS symptoms in Chinese patients with ALS, and these patients might have more serious physical, cognitive and frontal behaviour impairment. Patients with ALS might improve quality of life from the timely recognition and optimised management of EDS symptoms. Our results further suggest that ALS is a heterogeneous disease that might exhibit abnormal sleep-wake patterns.

  • amyotrophic lateral sclerosis
  • excessive daytime sleepiness
  • sleep disorders
  • cognition
  • behaviour

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  • SL and YH contributed equally.

  • Contributors SL: study concept, data acquisition and statistical analyses, interpretation of the results, writing the first version of the manuscript. YH: study concept, RLS diagnosis, interpretation of the results, revising the manuscript. LC: study concept, ALS diagnosis, FTD diagnosis, interpretation of the results, writing the final version of the manuscript. DS: revising the manuscript. HT, NS, HF, JS, KZ and ZW: revising the manuscript. QD: EMG study. ML, JG and YG: ALS diagnosis, FTD diagnosis, revising the manuscript.

  • Funding This study was funded by the National Key Research and Development Program of China (Grant number: 2016YFC0905100; 2016YFC0905103) and the Chinese Academy of Medical Sciences (CAMS) Innovation Fund for Medical Sciences (CIFMS) (Grant number: 2016-I2M-1-002; 2016-I2M-1-004).

  • Competing interests None declared.

  • Patient consent Not required.

  • Ethics approval This study was approved by the Research Ethics Committee of Peking Union Medical College Hospital.

  • Provenance and peer review Not commissioned; externally peer reviewed.