Sleep duration, cognitive decline, and dementia risk in older women

Alzheimers Dement. 2016 Jan;12(1):21-33. doi: 10.1016/j.jalz.2015.03.004. Epub 2015 Jun 15.

Abstract

Introduction: Consistent evidence linking habitual sleep duration with risks of mild cognitive impairment (MCI) and dementia is lacking.

Methods: We conducted a prospective study on 7444 community-dwelling women (aged 65-80 y) with self-reported sleep duration, within the Women's Health Initiative Memory Study in 1995-2008. Incident MCI/dementia cases were ascertained by validated protocols. Cox models were used to adjust for multiple sociodemographic and lifestyle factors, depression, cardiovascular disease (CVD), and other clinical characteristics.

Results: We found a statistically significant (P = .03) V-shaped association with a higher MCI/dementia risk in women with either short (≤6 hours/night) or long (≥8 hours/night) sleep duration (vs. 7 hours/night). The multicovariate-adjusted hazard for MCI/dementia was increased by 36% in short sleepers irrespective of CVD, and by 35% in long sleepers without CVD. A similar V-shaped association was found with cognitive decline.

Discussion: In older women, habitual sleep duration predicts the future risk for cognitive impairments including dementia, independent of vascular risk factors.

Keywords: Cognition; Cognitive decline; Cohort studies; Dementia; Elderly; Longitudinal analysis; Mild cognitive impairment; Sleep duration.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Cognitive Dysfunction / etiology*
  • Dementia / etiology*
  • Disorders of Excessive Somnolence / complications*
  • Female
  • Humans
  • Proportional Hazards Models
  • Prospective Studies
  • Risk Factors
  • Sleep Initiation and Maintenance Disorders / complications*
  • Sleep*