HealthDay News — Older people who have less slow wave sleep have higher levels of the brain protein tau, a marker of brain damage and Alzheimer disease (AD), according to a study published in the Jan. 9 issue of Science Translational Medicine.

Brendan P. Lucey, from the Washington University School of Medicine in St. Louis, and colleagues analyzed cognitive performance, brain imaging, and cerebrospinal fluid (CSF) AD biomarkers in 119 participants (>60 years) enrolled in a longitudinal study of aging. Additionally, participants’ sleep was monitored for six nights using a single-channel electroencephalography device worn on the forehead.

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After adjusting for multiple variables such as age and sex, the researchers found that nonrapid eye movement (NREM) sleep slow wave activity (SWA) was inversely related to AD pathology. Specifically, decreased NREM SWA was associated with higher levels of tau in the brain and a higher tau-to-amyloid ratio in the CSF. This association was most evident at the lowest frequencies of NREM SWA. There was no association between the total amount of sleep, just the quality of sleep, as measured by SWA.

“With the rising incidence of AD in an aging population, our findings have potential application in both clinical trials and patient screening for AD to noninvasively monitor for progression of AD pathology,” the authors write. “For instance, periodically measuring NREM SWA, in conjunction with other biomarkers, may have utility monitoring AD risk or response to an AD treatment.”

Several authors disclosed financial ties to pharmaceutical and biotechnology companies.

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