Lack of sleep is tied to increases in two Alzheimer’s proteins
It’s not just A-beta levels that rise in the sleep deprived; tau levels do too
A sleep-deprived brain is awash in excess amounts of not one but two proteins whose bad behavior is implicated in Alzheimer’s disease.
A new study finds excessive amounts of a protein called tau in the fluid that bathes the brain and spinal cord of extremely sleep-deprived adults. Tau, which is tied to nerve cell death, tangles and spreads throughout the brain during Alzheimer’s. An earlier report on these sleepy adults found that the protein amyloid-beta — globs of which dot the brains of Alzheimer’s patients — also increased.
Samples of cerebrospinal fluid collected from eight adults, monitored during a night of normal sleep and over the course of 36 hours of sleep deprivation, revealed a 51.5 percent increase in tau in participants robbed of shut-eye. And sleep-deprived mice had twice the amount of tau as well-rested mice, researchers report online January 24 in Science. Earlier work by these researchers had suggested that the quality of sleep might affect tau levels; this time, it’s been linked to duration of sleep.
With both A-beta and tau increasing with a lack of sleep, “it certainly argues that treating sleep disorders during mid-life as well as getting appropriate levels of sleep is likely to decrease risk for Alzheimer’s disease,” says coauthor David Holtzman, a neurologist and neuroscientist at Washington University School of Medicine in St. Louis. During sleep, the brain appears to flush out excess proteins and other debris (SN: 7/21/18, p. 22), so perhaps less sleep means that wash cycle is curtailed.