1140 ACTIGRAPHIC SLEEP AND BRAIN VOLUMES IN COMMUNITY-DWELLING OLDER ADULTS

Abstract

Introduction: Aging is associated with increases in the prevalence of sleep disturbance, which has been tied to cognitive impairment and decline. Disturbed sleep may lead to cognitive decline by promoting neurodegeneration. Thus, we investigated the association of objectively measured sleep with neuroimaging measures of brain volume in community-dwelling older adults. Methods: Participants were 183 older adults without dementia enrolled in the Baltimore Longitudinal Study of Aging who completed 3-T magnetic resonance imaging scans and wrist actigraphy. Total gray matter, white matter, ventricular, and hippocampal volumes were quantified using a multi-atlas approach to parcellation (MUSE software) and were our outcomes. Predictors were actigraphic sleep parameters averaged across nights, including total sleep time (TST), average wake bout length (WBL), % wake (% of sleep interval scored as wake), and sleep onset latency (SOL). Results: Participants had a mean ±SD age of 76.6 ± 8.8 years; 42.6% were male, 24% were non-White, and 84% had 16+ years of education. On average, they completed 6.8 ± 0.8 nights of actigraphy and had a TST of 394.5 ± 65.8 min, wake bout length of 2.5 ± 0.8 min, % wake of 11.7 ± 4.9, and SOL of 11.5 ± 14.5 min. After adjusting for age, sex, race, education, and intracranial volume, each SD increase in WBL was associated with a 3.52 unit increase in ventricular volume (B = 3.52, 95% confidence interval (CI) 0.80, 6.24, p = 0.012). In addition, each SD increase in % wake was associated with a 0.091 unit decrease in hippocampal volume (B = -0.091, 95% CI -0.18, -0.002, p = 0.045). There were no associations between TST or SOL and brain volumes. Conclusion: Greater objectively measured wakefulness is associated with indices of brain atrophy in community-dwelling older adults. Longitudinal research using actigraphy and neuroimaging is needed to better understand whether sleep has a role in the prevention of neurodegeneration. Support (If Any): This study was supported by Research and Development Contract HHSN-260-2004-00012C, R01AG050507, and 1RF1AG050745, and the Intramural Research Program, National Institute on Aging, NIH.