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Longer and more frequent naps predict incident Alzheimer’s dementia in community‐based older adults
Author(s) -
Li Peng,
Gao Lei,
Gaba Arlen,
Yu Lei,
Yaffe Kristine,
Buchman Aron S,
Bennett David A,
Hu Kun,
Leng Yue
Publication year - 2020
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1002/alz.045269
Subject(s) - dementia , actigraphy , medicine , audiology , alzheimer's disease , stroke (engine) , disease , cognition , psychology , gerontology , psychiatry , circadian rhythm , mechanical engineering , engineering
Background Excessive napping duration has been associated with cognitive decline. The effect of napping frequency is less understood, and little is known about the development of Alzheimer’s disease (AD) associated with napping. We tested whether longer or more frequent naps in the elderly are linked to the development of incident AD. Method We studied 1,180 older adults (age: 81.0±7.3 [SD]) in the Rush Memory and Aging Project who have been followed for up to 14 years. Motor activities (i.e., actigraphy; median length: 10 days; range: 2‐14 days) were recorded at baseline to assess napping characteristics objectively. We defined daytime napping episodes as motor activity segments between 10AM and 7PM with continuous zero‐activity for ≥10min but <1h (to avoid off‐wrist periods). Segments that were <5min apart were merged. Alzheimer’s dementia diagnosis was determined using the standard criteria (i.e., the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer’s Disease and Related Disorders Association). Cox proportional hazards models were performed to examine the associations of daily napping duration and frequency with incident AD. Result Of 1,180 non‐demented participants at baseline (including 264 with mild cognitive impairment), 277 developed Alzheimer’s dementia within 5.74±3.36 years. On average, participants napped for 38.3±1.0 (SE) min and1.56±0.04 (SE) times per day at baseline. After adjustment for age, sex, and education, every 30‐min increase in daily napping duration was associated with a 20% increase in the risk of incident AD (95% confidence interval [CI]: 9%‐31%; p =0.0002). One more nap per day was associated with a 19% increase in the risk of AD (95% CI: 8%‐30%; p =0.0003). These associations remained after adjustment separately for BMI, depressive symptoms, vascular diseases/risk factors, and other actigraphy‐derived measures including total daily activity, total sleep time, sleep fragmentation, stability and variability of daily activity rhythms. Conclusion Longer and more frequent daytime naps are associated with a higher risk of incident AD. Future studies are needed to examine specific underlying mechanisms.