title: Vitamin D Levels and the Risk of Cognitive Decline in Chinese Elderly People: the Chinese Longitudinal Healthy Longevity Survey.
abstract: Vitamin D has a neuroprotective function, potentially important for the prevention of cognitive decline. Prospective studies from Western countries support an association between lower vitamin D level and future cognitive decline in elderly people. No prospective study has examined this association in Asia.
  
  
  
  This community-based cohort study of elderly people in China follows 1,202 cognitively intact adults aged ≥60 years for a mean duration of 2 years. Plasma vitamin D level was measured at the baseline. Cognitive state of participants was assessed using the Mini-Mental State Examination (MMSE). Cognitive impairment was defined as an MMSE score <18. Cognitive decline was defined as ≥3 points decline from baseline. Multivariable logistic regression models were used to examine the association between quartiles of vitamin D levels with cognitive decline and incidence of cognitive impairment.
  
  
  
  Participants with low vitamin D level had an increased risk of cognitive decline. Compared with the highest quartile of vitamin D levels, the multivariable odds ratios (ORs; 95% confidence interval) for cognitive decline were 2.1 (1.3-3.4) for the second highest quartile, 2.2 (1.4-3.6) for the third highest quartile, and 2.0 (1.2-3.3) for the lowest quartile. The multivariable ORs of incident cognitive impairment for the second highest, third highest, and lowest versus highest quartiles of vitamin D levels were 1.9 (0.9-4.1), 2.6 (1.2-5.6), and 3.2 (1.5-6.6), respectively.
  
  
  
  This first follow-up study of elderly people, including the oldest-old, in Asia shows that low vitamin D levels were associated with increased risk of subsequent cognitive decline and impairment.
authors.affiliation: Health Services and Systems Research, Duke-NUS Medical School, Singapore. Department of Medicine, Duke University School of Medicine, Durham, North Carolina. david.matchar@duke-nus.edu.sg.
authors.forename: David B
authors.initials: DB
authors.lastname: Matchar
authors.affiliation: Health Services and Systems Research, Duke-NUS Medical School, Singapore. Department of Public Health Medicines, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.
authors.forename: Choy-Lye
authors.initials: CL
authors.lastname: Chei
authors.affiliation: Division of Non-Communicable Disease Control and Community Health, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Zhao-Xue
authors.initials: ZX
authors.lastname: Yin
authors.affiliation: Health Services and Systems Research, Duke-NUS Medical School, Singapore.
authors.forename: Victoria
authors.initials: V
authors.lastname: Koh
authors.affiliation: Centre for Quantitative Medicine, Duke-NUS Medical School, Singapore.
authors.forename: Bibhas
authors.initials: B
authors.lastname: Chakraborty
authors.affiliation: Division of Non-Communicable Disease Control and Community Health, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Shi
authors.affiliation: Center for the Study of Aging and Human Development and the Geriatric Division of School of Medicine, Duke University, Durham, North Carolina. Center for Healthy Aging and Development Studies, National School of Development, Raissun Institute for Advanced Studies, Peking University, Beijing, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zeng
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D002681:China / Q000453:epidemiology; D003072:Cognition Disorders / Q000453:epidemiology*; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008136:Longevity; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D012307:Risk Factors; D014807:Vitamin D / Q000097:blood; D014808:Vitamin D Deficiency / Q000453:epidemiology*
chemical_list: D014807:Vitamin D
keywords: Chinese elderly people; Cognitive decline; Cognitive impairment; Follow-up study; Vitamin D