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Reversible tau hyperphosphorylation in hibernation: a blood biomarker and brain tissue study
Wagner S Brum, Laia Montoliu-Gaya, Gunnar Brinkmalm, Diana Piotrowska, Elena Camporesi, Carsten Jäger, Helena S Isaksson, Sven Martin et al.. Acta neuropathologica, 2025-09-29
Topic: Plasma and spinal-fluid biomarkers
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) subjected to induced torpor (hibernation) versus euthermic (non-hibernating) states by quantifying multiple phosphorylated and non-phosphorylated tau peptides with an IP-MS method previously applied in human brain tissue. In brown bears, plasma levels of phosphorylated tau (p-tau) biomarkers p-tau181 and p-tau217 significantly increased during hibernation compared to summer (median increases of 362% and 294% by IP-MS, respectively), with similar increases found with immunoassays. Additional plasma p-tau biomarkers associated with AD pathology, including p-tau205 and p-tau231, were also increased during bear hibernation. In hamster brains, p-tau217, and p-tau231 were similarly elevated during torpor, while tau fragments from the microtubule-binding region (MTBR), associated with tangle aggregation, were not increased. In contrast, brain tissue from n = 10 AD patients, analyzed with the same IP-MS method, exhibited striking increases in p-tau (~ 50,000% for p-tau217) and MTBR fragments (~ 20,000% for MTBR tau354-369) compared with n = 10 human controls. We show that hibernation-linked tau hyperphosphorylation involves some of the same phospho-sites altered in AD, but occurs without MTBR tau aggregation. This highlights hibernation as a reversible, non-pathological model to study tau biology and mechanisms underlying AD due to its reversibility and lack of tau aggregation despite hyperphosphorylation in key AD tau phospho-sites.
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APA 7th
Brum, W. S., Montoliu-Gaya, L., Brinkmalm, G., Piotrowska, D., Camporesi, E., Jäger, C., et al. (2025). Reversible tau hyperphosphorylation in hibernation: a blood biomarker and brain tissue study. Acta neuropathologica. https://doi.org/10.1007/s00401-025-02930-2
Vancouver
Brum WS, Montoliu-Gaya L, Brinkmalm G, Piotrowska D, Camporesi E, Jäger C, et al. Reversible tau hyperphosphorylation in hibernation: a blood biomarker and brain tissue study. Acta neuropathologica. 2025. doi:10.1007/s00401-025-02930-2. PMID: 41023457.
BibTeX
@article{brum2025-41023457,
author = {Brum, Wagner S and Montoliu-Gaya, Laia and Brinkmalm, Gunnar and Piotrowska, Diana and Camporesi, Elena and Jäger, Carsten and Isaksson, Helena S and Martin, Sven and others},
title = {{Reversible tau hyperphosphorylation in hibernation: a blood biomarker and brain tissue study}},
journal = {Acta neuropathologica},
year = {2025},
doi = {10.1007/s00401-025-02930-2},
pmid = {41023457},
url = {https://doi.org/10.1007/s00401-025-02930-2}
}
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Key findings
- We also analyzed brain tissue from ten golden Syrian hamsters (Mesocricetus auratus) subjected to induced torpor (hibernation) versus euthermic (non-hibernating) states by quantifying multiple phosphorylated and non-phosphorylated tau peptides with an IP-MS method previously applied in human brain tissue.
- In brown bears, plasma levels of phosphorylated tau (p-tau) biomarkers p-tau181 and p-tau217 significantly increased during hibernation compared to summer (median increases of 362% and 294% by IP-MS, respectively), with similar increases found with immunoassays.
- Additional plasma p-tau biomarkers associated with AD pathology, including p-tau205 and p-tau231, were also increased during bear hibernation.
- In hamster brains, p-tau217, and p-tau231 were similarly elevated during torpor, while tau fragments from the microtubule-binding region (MTBR), associated with tangle aggregation, were not increased.
- In contrast, brain tissue from n = 10 AD patients, analyzed with the same IP-MS method, exhibited striking increases in p-tau (~ 50,000% for p-tau217) and MTBR fragments (~ 20,000% for MTBR tau354-369) compared with n = 10 human controls.
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Study details
- Evidence strengthLow
How this study scored 46/100
Published in a leading specialty journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record, multi-centre collaboration and free to read, so those were left out: it earned 26 of the 56 points we could judge it on, which is 46 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (Acta neuropathologica) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 4 / 5 | 2025 — within 3 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 41023457) |
| Free to read | — / 2 | Access not recorded — left out of this score |
| Points | 26 / 56 | Scored on 10 of 20 parts. We have no data for the rest, so they are left out: 26 of the 56 points we could judge it on is 46 out of 100. |
| Total | 46 / 100 | — |
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