Sleep‐Disordered Breathing and Cognition in Older Women

Abstract

To investigate the association between objectively measured sleep-disordered breathing (SDB) and cognitive impairment in community-dwelling older women and to determine whether the apolipoprotein E (APOE) epsilon4 allele modifies this association. Cross-sectional. Participants' homes and two sites of the Study of Osteoporotic Fractures (SOF). Four hundred forty-eight women with a mean age+/-standard deviation (SD) of 82.8+/-3.4. Participants completed the Mini-Mental State Examination (MMSE), Trail Making Test Part B (Trails B), and polysomnography (PSG). SDB indices were the apnea-hypopnea index (AHI), the central apnea index (CAI), and oxygen saturation (SaO2) nadir less than 80%. APOE epsilon4 was determined for a subset of 242 women. Cognitive impairment was defined as 1.5 SDs or more from the sample mean on either cognitive test (MMSE or Trails B). All SDB indices were associated with cognitive impairment according to the MMSE (AHI (per SD, odds ratio (OR)=1.4, 95% confidence interval (CI)=1.03-1.9), AHI of > or = 30 (OR=3.4, 95% CI=1.4-8.1), SaO2 nadir < 80% (OR=2.7, 95% CI=1.1-6.6), and CAI (per SD, OR=1.4, 95% CI=1.1-1.7)). Weaker, nonsignificant associations emerged between SDB and Trails B. In women who completed genotyping, each SD increase in AHI was associated with 70% greater odds of cognitive impairment according to the MMSE (OR=1.7, 95% CI=1.2-2.6). Women with the epsilon4 allele had a nearly five times greater odds of impairment (per SD, OR=4.6, 95% CI-1.0-20.7); the association was smaller and nonsignificant in women without the epsilon4 allele (per SD, OR=1.5, 95% CI-0.9-2.4; P for interaction=.08). SDB is an important risk factor for cognitive impairment in older women, especially those with the APOE epsilon4 allele. Mechanisms linking these disorders need to be identified.