biostudies-literatureBrum WSEuropean Research Council36https://www.ebi.ac.uk/biostudies/studies/S-EPMC12479634biostudies-literatureUnknown150(1)Tau hyperphosphorylation, a key neuropathological feature of tauopathies such as Alzheimer's disease (AD), also occurs physiologically during mammalian hibernation and is fully reversed upon arousal, offering a unique translational model to study tau metabolism. However, limited data exist on insoluble and soluble tau alterations during hibernation and on patterns of tau fragment concentrations in the hibernating mammalian brain. We quantified tau biomarkers in plasma samples from ten free-ranging brown bears (Ursus arctos), captured during both their active summer period and hibernation in the winter, using clinically validated immunoassays and immunoprecipitation mass spectrometry (IP-MS) techniques. We also analyzed brain tissue from ten golden Syrian hamsters (Mesocricetus auratus) subActa neuropathologicaReversible tau hyperphosphorylation in hibernation: a blood biomarker and brain tissue study.PMC12479634101096455Lashley TFerrari-Souza JPZimmer ERZetterberg HPiotrowska DKindberg JHolzer MBenedet ALMartin SStieler JTIsaksson HSJanelidze SHansson OCamporesi EJager CMontoliu-Gaya LAshton NJBrum WSBrinkmalm GArendt TFrobert OLantero-Rodriguez JMoscoso ABlennow KGobom JfalseReversible tau hyperphosphorylation in hibernation: a blood biomarker and brain tissue study.Tau hyperphosphorylation, a key neuropathological feature of tauopathies such as Alzheimer's disease (AD), also occurs physiologically during mammalian hibernation and is fully reversed upon arousal, offering a unique translational model to study tau metabolism. However, limited data exist on insoluble and soluble tau alterations during hibernation and on patterns of tau fragment concentrations in the hibernating mammalian brain. We quantified tau biomarkers in plasma samples from ten free-ranging brown bears (Ursus arctos), captured during both their active summer period and hibernation in the winter, using clinically validated immunoassays and immunoprecipitation mass spectrometry (IP-MS) techniques. We also analyzed brain tissue from ten golden Syrian hamsters (Mesocricetus auratus) sub2025-01-01T00:00:00Z2025 Sep2026-06-03T23:32:44.712Z2026-05-03T03:12:00.359ZS-EPMC124796344102345710.1007/s00401-025-02930-2