A US prospective, observational cohort study suggested that excessive daytime napping and dementia may possess a bidirectional relationship or share common pathophysiological mechanisms. The study examined the longitudinal change of daytime napping inferred objectively by actigraphy, and the association with incident Alzheimer’s dementia (AD) in 1401 participants (mean age 81.4 years, 76.5% female) during up to 14-year follow-up. Older adults tended to nap longer and more frequently with aging, while the progression of AD accelerates this change by more than doubling the annual increases in nap duration/frequency. Longer and more frequent daytime naps were associated with higher risk of AD. More excessive (longer or more frequent) daytime napping was correlated with worse cognition a year later, and conversely, worse cognition was correlated with more excessive naps a year later. The findings are consistent with prior studies and the association between excessive daytime napping and incident AD remained with similar effect sizes after adjustment for nighttime sleep quantity and quality including sleep duration, sleep fragmentation, and wake after sleep onset. The results indicate that there might be additional mechanism(s) beyond the adverse effects of nighttime sleep disturbances and may reflect the effect of AD pathology at preclinical stages. Source: https://alz-journals.onlinelibrary.wiley.com/
