title: Sleep quality and cognitive decline in a community of older adults in Daqing City, China.
abstract: OBJECTIVE
  To examine the association between self-reported sleep quality and cognitive decline one year later.
  
  
  METHODS
  A longitudinal study of 1010 cognitively intact adults, aged 65-80 years at baseline, from two urban communities in China was performed. Sleep quality at baseline was measured using the Pittsburgh Sleep Quality Index (PSQI). Cognitive function was determined by using the Chinese version of Mini-Mental State Examination (CMMSE) at the baseline and one year later. Substantial CMMSE decline was defined as the CMMSE score decreases by three or more points during the follow-up. Potential confounders, such as age, sex, education, baseline CMMSE score, depression, physical activity level, drinking status, smoking status, body mass index, snoring frequency, history of hypertension, diabetes, and coronary heart disease were measured via questionnaires or physical examination.
  
  
  RESULTS
  After adjusting for potential confounders, individuals with poor sleep quality (PSQI > 7), relative to whose with good sleep quality, had 0.32 (95% CI: -0.62, -0.02; p = 0.04) CMMSE-points more decline and tended to have a higher likelihood of developing substantial CMMSE decline (OR = 1.46; 95% CI: 0.97, 2.18; p = 0.06). Among seven subscales of the PSQI, poor sleep efficiency was associated with greater CMMSE decline (beta = -0.16, 95% CI: -0.29, -0.03; p = 0.01) and higher risk of substantial CMMSE decline (OR = 1.24, 95% CI: 1.05, 1.46; p = 0.01). Short sleep duration (sleeping ≤5 h/night) was also significantly associated with more CMMSE decline and a higher likelihood of developing substantial CMMSE decline (p <0.05 for both).
  
  
  CONCLUSIONS
  Self-reported poor sleep quality may be an indicator of early cognitive decline for elderly people and should be paid particular attention by clinicians.
authors: Department of Epidemiology and Bio-statistics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences/Peking Union Medical College, Beijing, China.
authors: Jinya
authors: J
authors: Niu
authors: Department of Epidemiology and Bio-statistics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences/Peking Union Medical College, Beijing, China.
authors: Huijun
authors: H
authors: Han
authors: Department of Epidemiology and Bio-statistics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences/Peking Union Medical College, Beijing, China.
authors: Yanhong
authors: Y
authors: Wang
authors: Department of Epidemiology and Bio-statistics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences/Peking Union Medical College, Beijing, China.
authors: Li
authors: L
authors: Wang
authors: Department of Nutritional Science, the Pennsylvania State University, University Park, PA, USA. Electronic address: xxg14@psu.edu.
authors: Xiang
authors: X
authors: Gao
authors: Department of Epidemiology and Bio-statistics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences/Peking Union Medical College, Beijing, China. Electronic address: susuliao@mx.cei.gov.cn.
authors: Susu
authors: S
authors: Liao
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002681:China; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology*; D003863:Depression / Q000523:psychology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009483:Neuropsychological Tests; D012893:Sleep Wake Disorders / Q000150:complications*; D011795:Surveys and Questionnaires
keywords: Cognition; Cognitive decline; Elderly; Sleep duration; Sleep quality