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What's the Link Between Poor Sleep in Youth & Later Risk for Alzheimer’s?

Quality and quantity of sleep remains a key concern among people with Alzheimer’s disease (AD).

As many as 40 percent of people with AD suffer from insomnia and other sleep disturbances.1 The data suggests that poor sleep among older people may directly link to the development and worsening of AD; meanwhile, poor sleep can impair memory processing, a common age-related symptom of AD.2,3

However, recent research suggests that focusing on older age may be a limited approach to understanding how poor sleep can influence the occurrence of AD.

Alzheimer’s risks identified in young men

A recent article in Neurology Today reports that when healthy young men experience acute sleep loss, this can affect the biomarkers researchers test for when trying to identify AD.4

A research trial conducted in Sweden found that changes in tau levels in younger research subjects suggested the possibility that, without adequate sleep, the brain—even in a younger person—may not adequately clear the toxins that can lead to AD.

Tau is the name of the protein found in high levels in the blood serum of people with AD. It’s considered a toxin the brain should clear during sleep.5 Mysteriously, it remains, something researchers continue to study.6

Researchers now use measurements of tau as biomarkers (identified in both blood serum and spinal fluid) to confirm AD even in its earliest stages, when symptoms may not otherwise be obvious.

In this latest research, young subjects underwent blood tests for tau levels on a normal night of sleep, followed by a single night of sleep deprivation. The scientists discovered that tau levels increased noticeably after the night of sleep loss.

Sleep deprivation can lead to inflammation in the brain, which in some people could potentially provide a “perfect storm” for tau accumulation over time.7 It begs the question, “When does Alzheimer’s begin?”

The study had limitations: its small size and a focus limited to young white men in good health. It’s hard to say if the same result would happen in women, people of color, or older people.

For this reason, more research needs to repeat these results and then expand upon them to better understand the relationship between sleep loss and rising tau levels.

Are circadian rhythms linked?

Circadian rhythms are the biological “clock” rhythms that all living things possess in relation to the day-night and light-dark cycles of the earth.

The circadian system of the human body is a key player in overall health and wellness. When circadian rhythms become disrupted, science shows that, time and again, this can lead to an illness that could become chronic.

Study investigator and author Jonathan Cedernaes, MD, PhD, wonders about a link between AD and the body clock. He’d also like to look for links between circadian rhythms and the onset of AD, which this study didn’t review.

“These findings could indicate that these proteins are controlled by a biological clock mechanism—that they exhibit so-called diurnal (daytime) or circadian rhythms,” Dr. Cedernaes told Neurology Today. “These findings should be viewed as an exploratory analysis, which needs to be confirmed in larger populations and under different settings of disrupted sleep and circadian rhythms.”

Alternately, Dr. Cedernaes suggests that researchers could look at the way AD itself disrupts both sleep and circadian rhythms to confirm the presence of a two-way, or bi-directional, relationship.

Areas for future research may include simulations of shift worker schedules as one way to test the role of disrupted circadian rhythms in younger people, focusing especially on those who experience sleep disturbances on a regular basis.

Other people with a known genetic risk for developing AD may consider this research as motivation to prioritize sleep while young and healthy.

“Taken together with evidence that sleep loss at an earlier age seems to be somewhat predictive of the risk of later developing Alzheimer's disease,” said Cedernaes, “we believe this at least provides an indication that even young individuals should take care of their sleep.”

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