Early Alzheimer Disease May Be Diagnosed Via Sleep Trackers
Older individuals who experience less slow-wave sleep have higher levels of the brain protein tau, according to a new study. Because elevated tau is a sign of Alzheimer disease (AD), this finding suggests that poor-quality sleep in older adults could be an indicator of deteriorating brain health.1
This new marker is an important step in the early intervention of AD.
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To establish the connection between lack of slow-wave sleep—the deep sleep individuals need to consolidate memories and wake up feeling refreshed—and increased tau levels, the researchers studied data on 119 participants aged 60 years or older.
Of the participants, who were recruited through the Charles F. and Joanne Knight Alzheimer’s Disease Research Center, 80% were considered cognitively normal and 20% were very mildly impaired.
To track sleep at home, the researchers gave each participant a portable electroencephalography monitor and a wristwatch-like senor. The former was strapped to the participants’ foreheads to measure their brain waves during sleep, while the latter tracked body movement.
The researchers also measured levels of amyloid beta and tau in the brain and in the cerebrospinal fluid that bathes the brain and spinal cord.
Nonrapid-eye movement sleep slow wave activity, especially at the lowest frequencies, was inversely related to AD pathology, particularly tauopathy. In turn, changes in such sleep activity, especially at 1 to 2 Hz, might be able to flag tau pathology and cognitive impairment either before or at the earliest stages of symptomatic AD.
The participants also kept sleep logs to record their nighttime sleep and daytime napping; daytime napping alone was significantly associated with high levels of tau.
“I do not expect sleep monitoring to replace brain scans or cerebrospinal fluid analysis for identifying early signs of Alzheimer disease, but it could supplement them,” said lead co-author Brendan Lucey. “It is something that could be easily followed over time, and if someone’s sleep habits start changing, that could be a sign for doctors to take a closer look at what might be going on in their brains.”2
—Colleen Murphy
References:
1. Lucey BP, McCullough A, Landsness EC, et al. Reduced non-rapid eye movement sleep is associated with tau pathology in early Alzheimer’s disease [published online January 9, 2019]. Sci Transl Med. doi:10.1126/scitranslmed.aau6550.
2. Decreased deep sleep linked to early signs of Alzheimer’s disease [press release]. St. Louis, MO: Washington University School of Medicine in St. Louis; January 9, 2019. https://medicine.wustl.edu/news/decreased-deep-sleep-linked-to-early-signs-of-alzheimers-disease/. Accessed January 9, 2019.