Alzheimer’s and daytime naps linked in new research

Resume: A study reveals a bidirectional link between daytime napping and cognitive decline associated with Alzheimer’s disease. The researchers say that longer and more frequent naps were associated with worse cognition after one year, and worse cognition was linked to longer and more frequent daytime naps.

Source: Rush University Medical Center

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

The connection appears to run in both directions, the researchers say; longer and more frequent naps were 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 a co-author of the paper, said the study adds evidence to changing views about Alzheimer’s disease as a purely cognitive disorder.

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

The researchers followed more than 1,400 patients for up to 14 years as part of the Rush Memory and Aging Project and the Religious Orders Study. Participants wore a sensor on their wrist that recorded activity continuously for up to 10 days and returned once a year for exams and cognitive tests. Any prolonged period of inactivity during the day from 9 am to 7 pm was considered a nap.

When the study began, more than 75% of the participants showed no signs of cognitive decline, 19.5% had mild cognitive impairment, and just over 4% had Alzheimer’s disease dementia.

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

The researchers also compared participants who had normal cognition at the start of the study but developed Alzheimer’s disease dementia with their counterparts whose thinking remained stable during the study. They found that older people who slept more than an hour a day had a 40% increased risk of developing Alzheimer’s.

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

“This is an observational study, so we can’t say ‘a causes b,'” he said. “But we can say that they develop at the same time, and it is possible that the same pathologies contribute to both.”

Alzheimer’s disease is caused by the buildup of two proteins, amyloid beta and tau, within the brain. While decreased cognitive function is the most well-known symptom of Alzheimer’s disease, this protein buildup can occur in various locations in the brain, brainstem, and spinal cord, causing a variety of symptoms.

The study adds evidence to changing views of Alzheimer’s disease as a purely cognitive disorder. The image is in the public domain

The study indicates that increases in the frequency and duration of naps during the day may be one of those symptoms.

“Once you’ve identified the pathology and location, you can work on potential treatments,” Buchman said. “There are proteins or genes that could prevent the buildup of tau and beta, or there are potential ways to mitigate or slow their buildup.”

The study was supported by the National Institutes of Health and the BrightFocus Foundation Alzheimer’s Research Program. Buchman said one of the main strengths of the study was the cohorts of participants from the Memory and Aging Project and the Religious Orders Study. Both studies are decades-long efforts that recruit participants to undergo annual testing, sample collection and organ donation after death.

“The people in our studios are very special people,” he said. “Without the people who make this kind of contribution, we wouldn’t be able to do the research that we do. They are so excited to be able to participate that they encourage the staff with their participation. We are very lucky to have them.”

About this Alzheimer’s disease research news

Author: press office
Source: Rush University Medical Center
Contact: Press Office – Rush University Medical Center
Image: The image is in the public domain.

original research: Closed access.
“Daytime napping and Alzheimer’s dementia: a possible bidirectional relationship” by Peng Li et al. Alzheimer’s and dementia


Resume

See also

This is a cartoon of a man holding his head in pain.

Daytime napping and Alzheimer’s dementia: a possible bidirectional relationship

Introduction

Daytime naps are frequently seen in older adults. The longitudinal relationship between daytime napping and cognitive aging is unknown.

Methods

Using data from 1401 Rush Memory and Aging Project participants, we examined the longitudinal change of objectively inferred daytime napping by actigraphy and the association with incident Alzheimer’s dementia during up to 14 years of follow-up.

Results

Older adults tended to nap longer and more frequently with age, while the progression of Alzheimer’s dementia accelerates this change by more than doubling annual increases in nap length/frequency. Longer and more frequent daytime naps were associated with an increased risk of Alzheimer’s dementia. Interestingly, more excessive daytime naps (longer or more frequent) were correlated with worse cognition one year later, and conversely, worse cognition was correlated with more excessive naps one year later.

Discussion

Excessive daytime napping and Alzheimer’s dementia may have a bidirectional relationship or share common pathophysiological mechanisms.

Leave a Comment