Deep sleep can protect older adults from Alzheimer’s-related memory loss

BERKELEY, Calif. — There isn’t much that a good night’s sleep can’t do. Now, a new study is reinforcing the importance of getting good quality sleep as we age. Researchers from the University of California-Berkeley find that deep sleep can protect older adults from Alzheimer’s-related memory loss.

“With a certain level of brain pathology, you’re not destined for cognitive symptoms or memory issues,” explains Zsófia Zavecz, a postdoctoral researcher at UC Berkeley’s Center for Human Sleep Science. “People should be aware that, despite having a certain level of pathology, there are certain lifestyle factors that will help moderate and decrease the effects.”

“One of those factors is sleep and, specifically, deep sleep,” the researcher continues in a university release.

Previously, studies have linked poor sleep to a faster accumulation of beta-amyloid protein in the brain, which is the hallmark of Alzheimer’s disease development. One of the most disruptive parts of having the condition is memory loss, related to destroyed memory pathways that can make performing daily tasks difficult.

Years of education, physical activity, and social engagement are widely referred to as cognitive reserve factors, helping to keep people’s brain sharp. The problem with better education or engaging in more physical activity is that these aren’t easily modifiable later in life, so patients can’t quickly change those factors during old age.

That led UC Berkeley professor of neuroscience Matthew Walker to pose an important question.

“If we believe that sleep is so critical for memory, could sleep be one of those missing pieces in the explanatory puzzle that would tell us exactly why two people with the same amounts of vicious, severe amyloid pathology have very different memory?”

“If the findings supported the hypothesis, it would be thrilling, because sleep is something we can change,” Prof. Walker adds. “It is a modifiable factor.”

Beta-Amyloid Plaques
In the Alzheimer’s affected brain, abnormal levels of the beta-amyloid protein clump together to form plaques (seen in brown). Credit: National Institute on Aging, NIH. All Rights Reserved.

To explore this, the team recruited 62 older healthy adults without dementia from the Berkeley Aging Cohort Study. The participants slept in a lab while researchers monitored their sleep waves with an electroencephalography (EEG) machine. The team also used a positron emission tomography (PET) scan to measure the amount of beta-amyloid deposits in the participants’ brains. Half had large deposits, while the other half didn’t. After sleeping, the participants had to match names to faces based on memory.

Researchers found that participants with high amounts of amyloid deposits in their brain that slept deeply performed better on the memory test than those with the same levels of deposits who slept worse. In those without deposits, deep sleep didn’t yield any additional support for memory.

“Think of deep sleep almost like a life raft that keeps memory afloat, rather than memory getting dragged down by the weight of Alzheimer’s disease pathology,” says Walker. “It now seems that deep NREM sleep may be a new, missing piece in the explanatory puzzle of cognitive reserve. This is especially exciting because we can do something about it. There are ways we can improve sleep, even in older adults.”

Although this study was relatively small, it still points to what we already know: quality sleep matters. The research also paves the way for potential longer-term experiments that explore sleep-enhancement treatments and their implications on cognitive outcomes.

The findings are published in the journal BMC Medicine.

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About the Author

Shyla Cadogan, RD

Shyla Cadogan is a DMV-Based acute care Registered Dietitian. She holds specialized interests in integrative nutrition and communicating nutrition concepts in a nuanced, approachable way.

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