title: Measures of Sleep-Wake Patterns and Risk of Mild Cognitive Impairment or Dementia in Older Women.
abstract: OBJECTIVE
  Sleep disturbances are common in older adults. Little is known about the sleep of cognitively intact older adults and its relationship to subsequent cognitive impairment. The objective of this study was to examine the association between objective sleep-wake measures and risk of incident cognitive impairment.
  
  
  METHODS
  In this prospective cohort study encompassing four U.S. sites, 1,245 women (mean age: 82.6 years) without dementia participated in the Study of Osteoporotic Fractures and completed actigraphy at the baseline visit and comprehensive cognitive assessment at follow-up. The association between sleep-wake patterns measured by actigraphy and risk of incident mild cognitive impairment (MCI) and dementia was examined.
  
  
  RESULTS
  A total of 473 women (38%) developed cognitive impairment during an average (SD) follow-up of 4.9 (0.6) years; 290 (23.3%) developed MCI and 183 (14.7%) developed dementia. After controlling for multiple potential confounders, women in the lowest quartile of average sleep efficiency (<74%) had a 1.5-fold higher odds of developing MCI or dementia compared with women in the highest quartile of sleep efficiency (>86%) (odds ratio: Q1 versus Q4 1.53; 95% CI: 1.07, 2.19; Wald χ(2) [1, N = 1,223] = 5.34 for p for trend = 0.03). Longer average sleep latency, but not total sleep time, was also associated with higher odds of developing cognitive impairment. Greater variability in both sleep efficiency and total sleep time was associated with an increased odds of developing MCI or dementia.
  
  
  CONCLUSIONS
  Lower average sleep efficiency, longer average sleep latency, and greater variability in sleep efficiency and total sleep time are associated with increased odds of developing cognitive impairment. Further research is needed to explore the mechanisms underlying these associations.
authors.affiliation: Department of Medicine and Division of Epidemiology & Community Health, University of Minnesota, Minneapolis, MN. Electronic address: sdiem@umn.edu.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Diem
authors.affiliation: California Pacific Medical Center Research Institute, San Francisco, CA.
authors.forename: Terri L
authors.initials: TL
authors.lastname: Blackwell
authors.affiliation: California Pacific Medical Center Research Institute, San Francisco, CA.
authors.forename: Katie L
authors.initials: KL
authors.lastname: Stone
authors.affiliation: Departments of Psychiatry, Neurology, and Epidemiology, University of California, San Francisco and the San Francisco VA Medical Center, San Francisco, CA.
authors.forename: Kristine
authors.initials: K
authors.lastname: Yaffe
authors.affiliation: California Pacific Medical Center Research Institute, San Francisco, CA.
authors.forename: Greg
authors.initials: G
authors.lastname: Tranah
authors.affiliation: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA.
authors.forename: Jane A
authors.initials: JA
authors.lastname: Cauley
authors.affiliation: Departments of Medicine and Psychiatry, University of California, San Diego, CA.
authors.forename: Sonia
authors.initials: S
authors.lastname: Ancoli-Israel
authors.affiliation: Department of Medicine, Brigham and Women's Hospital and Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.
authors.forename: Susan
authors.initials: S
authors.lastname: Redline
authors.affiliation: Department of Mental Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Spira
authors.affiliation: Kaiser Permanente Center for Health Research, Portland, OR.
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Hillier
authors.affiliation: Department of Medicine and Division of Epidemiology & Community Health, University of Minnesota, Minneapolis, MN; Center for Chronic Disease Outcomes Research, Minneapolis VA Health Care System, Minneapolis, MN.
authors.forename: Kristine E
authors.initials: KE
authors.lastname: Ensrud
mesh_terms: D056044:Actigraphy; D000369:Aged, 80 and over; D000375:Aging / Q000523:psychology*; D060825:Cognitive Dysfunction / Q000150:complications* / Q000523:psychology*; D003704:Dementia / Q000150:complications* / Q000523:psychology*; D005260:Female; D006801:Humans; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012307:Risk Factors; D007319:Sleep Initiation and Maintenance Disorders / Q000150:complications* / Q000523:psychology*
keywords: actigraphy; cognitive aging; dementia; older women; sleep disorders