One night of sleep deprivation could increase Alzheimer’s biomarker, study finds

Written by Kate Lovesey, Future Science Group

Researchers have published a study in Neurology detailing that the percentage of an Alzheimer’s biomarker – tau – is found at elevated levels in the plasma of sleep-deprived, healthy, young men.

The protein, tau is located within neurons that can form tangles and accumulate in the brains of individuals with Alzheimer’s disease. Accumulation of tau can start to develop in the brain decades before symptoms of Alzheimer’s disease are diagnosed. Previous studies of elderly participants have suggested that sleep deprivation can increase the percentage of tau in cerebral spinal fluid. It has also been reported that head trauma can increase circulating concentrations of tau in the blood.

The corresponding author, Jonathan Cedernaes (University in Sweden, Uppsala, Sweden) explained:  “Many of us experience sleep deprivation at some point in our lives due to jet lag, pulling an all-nighter to complete a project, or even doing shift work, working overnights or inconsistent hours. Our exploratory study shows that even in young, healthy individuals, missing one night of sleep increases the level of tau in blood suggesting that over time, such sleep deprivation could possibly have detrimental effects.”

The participants of the study consisted of 15 healthy, normal-weight men with an average age of 22. The men all reported that they regularly receive 7­–9 hours of quality sleep each night. For each phase of the two-phase study, the men were observed under a strict meal and activity schedule in a sleep clinic for 2 days and nights with blood samples taken daily in the evening and morning.

Researchers discovered that participants had an average 17% increase of tau in their blood after a night of sleep deprivation, compared to an average 2% increase of tau after a good night’s sleep. Although researchers also examined four other biomarkers associated with Alzheimer’s disease, the results demonstrated no changes in biomarker levels between a good night’s sleep and one of sleep deprivation.

The exploratory study is limited by its small sample size and variation, with all participants being healthy young men. the results cannot be generalized to women or elderly individuals.

Jonathan Cedernaes added: “It’s important to note that while higher levels of tau in the brain are not good, in the context of sleep loss we do not know what higher levels of tau in blood represent. When neurons are active, production of tau in the brain is increased. Higher levels in the blood may reflect that these tau proteins are being cleared from the brain or they may reflect elevated tau levels in the brain. Future studies are needed to investigate this further, as well as to determine how long these changes in tau last, and to determine whether changes in tau in blood reflects a mechanism by which recurrent exposure to restricted, disrupted or irregular sleep may increase the risk of dementia. Such studies could provide key insight into whether interventions targeting sleep should begin at an early age to reduce a person’s risk of developing dementia or Alzheimer’s disease.”

Sources: Benedict C, Blennow K, Zetterberg H, Cedernaes J. Effects of acute sleep loss on diurnal plasma dynamics of CNS health biomarkers in young men. Neurology, doi:10.1212/WNL.0000000000008866 (2019)(Epub);