Preclinical cognitive decline and subsequent sleep disturbance in older women.

OBJECTIVE: To determine whether longitudinal cognitive decline is associated with increased risk of sleep disturbance in older, nondemented, community-dwelling women.
METHODS: We studied 2,474 women (mean age 68.9 years) who were part of a prospective study started in 1986; women with baseline or follow-up evidence of possible dementia were excluded. Cognitive data were gathered over 15 years for modified Mini-Mental State Examination (mMMSE) and 13 years for Trails B; cognitive decline was defined as declining >1.5 SDs on the mMMSE (> or =3 points) or Trails B (>92 seconds). Sleep disturbance was measured objectively using actigraphy (Sleepwatch-O, Ambulatory Monitoring) at the 15-year follow-up visit; measures included total sleep hours, sleep efficiency, sleep latency, napping, and time awake after sleep onset (WASO).
RESULTS: During follow-up, 11% of women declined on mMMSE and 15% on Trails B. Cognitive decliners were more likely than non-decliners to experience sleep disturbance at follow-up on most measures. For women who declined on mMMSE, adjusted ORs (aOR) (95% CI) were 1.71 (1.24, 2.37) for sleep efficiency <70%, 1.57 (1.12, 2.21) for sleep latency > or =1 hour, and 1.43 (1.07, 1.92) for WASO > or =90 minutes. Results were similar for women who declined on Trails B; in addition, these women were more likely to nap >2 hours per day (aOR: 1.73; 95% CI: 1.28, 2.33). Cognitive decline on either test was not associated with total sleep time.
CONCLUSIONS: Cognitive decline is associated with sleep disturbance in nondemented community-dwelling elderly women.