Losing sleep can make you cranky, impact your stress levels, and lead to health problems–and a new study finds that losing just one night of sleep increases levels of a protein that could lead to Alzheimer’s Disease.
The protein is called tau, and it is contained within mature neurons where it functions as a “microtubule-associated protein.” Microtubules are thread-like structures within the cells which provide structural support and facilitate movements within the cell, such as moving chromosomes during cell division, or guiding proteins carrying cell components around the cell.
Previous studies on tau has found that it is present in large quantities in the brains of Alzheimer’s patients, where the thread-like microtubules form neurofibrillary tangles which build up over time. Since tau is normally a protein which is unfolded in the brain, it becomes harmful when it is tangled over on itself and cannot assist the microtubules in cell functioning.
Tau accumulations can be found in other neurodegenerative diseases such as dementia and prion diseases. In the disease process of dementia (specifically frontotemporal dementia, or FTD), tau is abnormally deposited in the temporal and frontal lobes which govern executive function and behavior.
Tau is increased after head trauma and has been noted to increase after periods of sleep deprivation, but previous research only involved older adults. The research team at Sweden’s Uppsala University investigated the effects of sleep deprivation on healthy, young adults and how their tau levels were affected.
The test participants were men around 22 years old on average, and their blood was analyzed at the start and end of each day. The study ran for 4 days in a sleep clinic. For control purposes, participants slept normally on two nights in the first phase of the study. The second phase involved participants sleeping normally for a night and were then deprived of sleep the second night. The participants were not allowed to sleep at all during this period, and they were asked to stay awake with the lights on while they watched movies, played games, or talked with one another.
During the phase in which they could sleep normally, tau increased in their blood levels by 2%–but after just one night of sleep deprivation, their tau levels increased by 17%. The study notes that the results have limitations because it is still unknown what the higher blood levels of tau mean with regard to sleep. The accumulation of tau within the brain is known to be toxic, but further research is needed to understand what tau in the blood represents.
Traditional measurements of tau in the body have come from cerebrospinal fluid analysis. When tau is found in cerebrospinal fluid, it is believed to be due to the disintegration of dying neurons; but tau in blood could mean that the tau is either being shed and released from the brain or that it is indicative of the current concentration of tau in the brain.
Either way, this study represents yet another reason to aim for a good night’s sleep and provides another look at the tau protein from another angle.
Benedict, Christian, et al. “Effects of Acute Sleep Loss on Diurnal Plasma Dynamics of CNS Health Biomarkers in Young Men.” Neurology, 8 Jan. 2020, doi:https://doi.org/10.1212/WNL.0000000000008866.
Pirscoveanu, DFV, et al. “Tau Protein in Neurodegenerative Diseases – a Review.” Rom J Morphol Embryol, vol. 58, no. 4, 2017, pp. 1141–1150., https://www.ncbi.nlm.nih.gov/pubmed/29556602.
Mandelkow, Eva-Maria, and Eckhard Mandelkow. “Biochemistry and cell biology of tau protein in neurofibrillary degeneration.” Cold Spring Harbor perspectives in medicine vol. 2,7 (2012): a006247. doi:10.1101/cshperspect.a006247