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 χ2 [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. Conclusion 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.
Bibliographical noteFunding Information:
The Study of Osteoporotic Fractures is supported by grants RO1 AG005407 , RO1 AR35582 , ROA AR35583 , RO1 AR35584 , RO1 AG005394 , RO1 AG027574 , RO1 AG027576 , and KO1 AG033195 from the National Institute on Aging . The funding agencies had no direct role in the conduct of the study; the collection, management, analyses and interpretation of the data; or preparation or approval of the manuscript. All authors have nothing to disclose.
© 2016 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.
Copyright 2016 Elsevier B.V., All rights reserved.
- cognitive aging
- older women
- sleep disorders