A newly published study was able to find that the loss of sleep, even for one night, in healthy young men can increase the levels of tau protein in their blood compared to those who are getting a proper, complete and uninterrupted sleep. The studies have shown that higher levels of tau protein in the blood are linked with an increased risk of having Alzheimer's disease later on in life.
Study author Dr. Jonathan Cedernaes, a neurologist at Uppsala University in Sweden stated that their study shows that even in young and healthy people, missing one night of sleep can increase the level of tau in their blood, thus suggesting that over time, sleep deprivation could possibly have detrimental effects. The study was published in Neurology, the medical journal of the American Academy of Neurology.
What is tau?
Tau is a protein that can help stabilize the internal makeup of our brain nerve cells, according to the Alzheimer's Association. An abnormal form of tau builds up in Alzheimer's and it causes the interior of the cells to fall apart. When these abnormal tau proteins clump, they all form tangles, which is a key sign of Alzheimer's, Lewy body disease and frontal lobe dementia.
Tau and other toxins in the brain are cleared away during sleep in a healthy individual, sort of like taking out the garbage at night. Losing sleep, or even having disordered sleep in which the sleep cycles are disrupted, can interfere with the brain's ability to clean up.
Mayo Clinic neurologist, Dr. Donn Dexter, stated that when we get more of that deep sleep and you get the REM sleep in the normal amounts, that improves the clearance of abnormal proteins which we think is great. Dr. Donn Dexter is not involved in the study, but he is associated with the American Academy of Neurology.
Sleep deprivation and cognitive issues
In addition to this discovery, numerous studies have shown that sleep deprivation can also allow more tau to develop and even accumulate. This suggests that poor sleep can hasten the development of cognitive issues. A study that was published back in 2017 found that healthy, middle-aged adults who slept badly for just one night produced an abundance of the protein called beta-amyloid, responsible for the plaques characteristic of Alzheimer's. A week of disrupted sleep increased the amount of tau in the blood.
In this particular study, the researchers found that men who were not allowed to sleep had about 17% chance of increasing tau in their blood. Men who had a good night's sleep only showed a 2% chance of increasing tau in their blood. Researchers caution that the study is inconclusive and small, and they acknowledge that they were not able to know what the increased levels might mean.
Cedernaes said that higher levels in the blood may reflect that these tau proteins are being cleared from the brain or they may even reflect elevated tau levels in the brain. More future studies are needed to investigate this further.
Dexter agreed that the study raises more questions than answers and that what the study is telling us is that researchers need to dig more deeply. Despite something that we do for a third of our lives, we know so little about sleep and we are learning something new about it every day, particularly when it comes to dementia and sleep.
