Alzheimer’s disease and daytime napping are linked in new research – Neuroscience News

Summary: The study reveals a two-way 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 that worse cognition was linked to longer and more frequent naps during the day.

Source: Rush University Medical Center

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

The connection seems to go both ways, 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 co-author of the paper, said the study provides evidence for the development of vision in Alzheimer’s disease as a purely cognitive disorder.

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

Researchers followed more than 1,400 patients for 14 years as part of the Rush Memory and Aging Project and the Religious Order Study. Participants wore a wrist-worn sensor that recorded activity continuously for up to 10 days and came in once a year for checkups and cognitive testing. Any prolonged period of inactivity during the day from 9 a.m. to 7 p.m. was considered a nap.

At the start of the study, more than 75% of participants showed no signs of cognitive impairment, 19.5% had mild cognitive impairment and just over 4% suffered from dementia related to Alzheimer’s disease.

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

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

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 you could say they’re happening at the same time, and it’s possible that the same pathologies are contributing to both.”

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

The study indicates that increased frequency and duration of daytime naps may be one such symptom.

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

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

“The people who take part in our studies are very special people,” he said. “Without 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 animate 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
Picture: Image is in public domain

Original research: Access closed.
“Daytime Napping and Alzheimer’s Dementia: A Potential Bidirectional Relationship” by Peng Li et al. Alzheimer’s and dementia

---

Abstract

Daytime Napping and Alzheimer’s Dementia: A Potential Bidirectional Relationship

Introduction

Daytime naps are common among older people. The longitudinal relationship between daytime naps and cognitive aging is unknown.

Methods

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

Results

Older people tend to take longer and more frequent naps with age, while the progression of Alzheimer’s dementia accelerates this change by more than doubling annual increases in nap duration/frequency. Longer and more frequent naps during the day were associated with a higher risk of Alzheimer’s dementia. Interestingly, more excessive (longer or more frequent) daytime naps were correlated with worse cognition one year later, and conversely, worse cognition was correlated with more excessive naps one year later.

Discussion

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