Alzheimer’s and Sleep

You would assume that a quick nap in the afternoon is good. You feel a little drowsy in the afternoon and decide to take a quick nap. According to a study in the journal JAMA Neurology, drowsiness in the afternoon might not be a good thing, especially for older adults. The research found that the symptom could be an early indication of Alzheimer’s disease.

Previous studies have determined that a build-up of amyloids, a protein, in the brain is an early symptom of Alzheimer’s. The JAMA study found a relationship between sleep disruptions at night and the build-up of amyloids. So, they concluded that some relationship must exist between feeling drowsy during the day and Alzheimer’s.

It’s been known for some time that sleep is important to brain health. Sleep is part of the daily cycle of life. It allows the brain to rest and reset itself. Research has shown that we need between seven and eight hours of sleep a day.

“We know that sleep is necessary to clear toxins and beta-amyloid in the brain,” said Prashanthi Vemuri, a professor at the Mayo Clinic, who helped author the study, in a CNN interview. “We also know that beta-amyloid causes sleep disruptions. So, it’s been a chicken and an egg problem.”

For the study, the researchers recruited 3,000 people who were 70 years or older and were already participating in a Mayo Clinic study on aging. A baseline scan was taken of people who wanted to participate in the study. They were also required to fill out a questionnaire. The researchers wanted to make sure people weren’t already suffering from the early stages of dementia. In the end, they selected 283 participants for the study. The research took two years to complete, and the participants agreed to have multiple brain scans conducted on them over that period.

Sleep Instability

A key finding in the study was the relationship between daytime drowsiness and sleep instability. The researcher found no noticeable difference in the build-up of amyloid in the brain between participants who suffered from sleep apnea and those who did not. They say further research is needed in this area.
Rather general sleep instability associated with non–rapid eye movement (NREM) sleep seemed to be the greater cause of the build-up of amyloids in the brain. People who suffered from this type of sleeping disorder were more likely to suffer from excessive daytime sleepiness. The researchers surmised that heavy sleepiness during the daytime “could affect the propagation of slow waves, generating more sleep instability.”

The findings, they said, were in line with other sleep studies about elderly people, and they found that many of the participants already showed sign of amyloids in the brain. Excessive daytime sleepiness seemed to speed up the process.

First-of-its-kind Study

The study was the first-of-its-kind to establish biomarkers between Alzheimer’s and sleep deprivation. The researchers say that more work needs to be done in this area, but the study gives physicians information when making recommendations to patients. They can emphasize the need to get a solid night of sleep.

“I would hope that people understand that good sleep habits are important to have a healthy brain since it can prevent amyloid, which is one of the primary proteins underlying Alzheimer’s disease,” said Vemuri in an interview with Time.

Joseph R. Winer, of the University of California, Berkeley, and Bryce A. Mander, of the University of California, Irvine, wrote an editorial that accompanied the study entitled “Waking Up to the Importance of Sleep in the Pathogenesis of Alzheimer Disease.” Winer was impressed with the results and said it was good that a link between sleep and Alzheimer’s had been found.

“What we’re excited about is that it’s the first to show longitudinal evidence in humans,” Winer said in an interview with CNN. “Most of our evidence has come from mice studies and looking at people at a one-time point. This is the first study that followed people over time.”

The study showed that amyloids build up the most in areas of the brain associated with emotion, memory retrieval and behavior. They say that more research needs to be done among people who are in the 40s and 50s when amyloids begin to develop. Once people are older, it can be difficult to stop slow down the effects of amyloid build up.

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