Alzheimer’s and Daytime Napping Linked in New Research

Could there be a link between cognitive decline and excessive daytime napping? New research from the Rush Alzheimer’s Disease Center suggests a potential connection, according to an article published in Alzheimer’s and Dementia.

The connection appears to occur in both directions, researchers say; longer and more frequent napping was correlated with worse cognition after one year, and worse cognition was correlated with longer and more frequent naps after one year.

Aron Buchman, MD, a neurologist at Rush University Medical Center and co-author of the article, said the study lends evidence to the changing views of Alzheimer’s disease as a purely cognitive disorder.

“We now know that the pathology related to cognitive decline can cause other changes in function,” he said. “It’s really a multi-system disorder, also including difficulty sleeping, changes in movement, changes in body composition, depression symptoms, behavioral changes, etc.”

Participants wore a wrist-worn sensor that recorded activity continuously for up to 10 days, and came in once a year for examinations and cognitive testing. Any prolonged period of no activity during the daytime from 9 a.m. to 7 p.m. was considered a nap.

When the study started, more than 75% of participants showed no signs of any cognitive impairment, 19.5% had mild cognitive impairment and slightly more than 4% had Alzheimer’s disease dementia.

Daily napping increased by about 11 minutes per year among those who didn’t develop cognitive impairment during follow-up. Naps doubled after a diagnosis of mild cognitive impairment, and nearly tripled after a diagnosis of Alzheimer’s disease dementia.

Researchers also compared participants who had normal cognition at the start of the study but developed Alzheimer’s disease dementia to their counterparts whose thinking remained stable during the study. 

Buchman stressed that the study does not imply that napping causes Alzheimer’s dementia, or vice versa.