Rest-Activity Rhythms and Cognitive Decline in Older Men: The Osteoporotic Fractures in Men Sleep Study

Objective: To examine rest–activity circadian rhythm (RAR) and cognitive decline in older men. Design: Longitudinal. Setting: Osteoporotic Fractures in Men (MrOS) and ancillary Outcomes of Sleep Disorders in Men (MrOS Sleep) studies. Participants: MrOS and MrOS Sleep participants (N=2,754; mean age 76.0 ± 5.3). Measurements: The Modified Mini-Mental State examination (3MS) was used to assess cognition at baseline (2003–05) and follow-up examinations (2005–06 and 2007–09). Wrist actigraphy was used to measure 24-hour activity counts at baseline. RAR variables included amplitude (strength of activity rhythm), mesor (mean activity level), pseudo F-statistic (overall circadian rhythm robustness), and acrophase (time of daily peak activity). Results: After an average of 3.4 ± 0.5 years, men with lower amplitudes, mesors, and pseudo F-statistics had greater decline in 3MS performance (amplitude: –0.7 points Q1 vs –0.5 points Q4, p<.001; mesor: –0.5 points Q1 vs –0.2 points Q4, p=.01; pseudo F-statistic: –0.5 points Q1 vs –0.3 points Q4, p<.001). Lower amplitudes and pseudo-F statistics were associated with greater odds of clinically significant cognitive decline (≥5-point decrease) (amplitude Q1 vs. Q4: odds ratio (OR)=1.4, 95% confidence interval (CI)=1.0–1.9; pseudo-F statistic Q1 vs Q4: OR=1.4, 95% CI=1.0–1.9). Men with phase-advanced acrophase had greater odds of clinically significant cognitive decline (OR=1.8, 95% CI=1.2–2.8). Results were adjusted for multiple confounders. Conclusion: Several parameters of disrupted RAR (lower amplitude, pseudo F-statistic, mesor, phase-advanced acrophase) were associated with greater cognitive decline in older community-dwelling men. These findings contribute to a growing body of evidence suggesting that altered RARs are associated with cognitive decline in older adults. J Am Geriatr Soc 66:2136–2143, 2018.