A blood protein marker developed for Alzheimer's disease may also help identify chronic traumatic encephalopathy in living people, according to preliminary research reported by Science News on July 31. Researchers found that levels of eMTBR-tau243 rose with the severity of CTE confirmed after death, but stressed that the small study is not yet a diagnostic test.
CTE is a progressive brain disease associated with repeated head impacts, including exposure in contact sports. Doctors can currently confirm it only by examining brain tissue after death, leaving patients and researchers without a validated biological test during life. The disease involves abnormal deposits of tau, a protein that normally helps support and transport materials inside nerve cells.
Washington University neuroscientists Kanta Horie and Chihiro Sato first evaluated eMTBR-tau243 while developing an Alzheimer's assay. In cerebrospinal fluid from 112 people with eight brain diseases, elevated levels appeared mainly in Alzheimer's cases, apart from a surprising patient with advanced CTE. That observation led the team to study samples linked to donated brains with confirmed pathology.
The researchers examined blood from 11 donors whose brains showed CTE. The marker was higher than in healthy controls and increased by pathological stage: Stage I cases had significantly lower levels than Stage IV cases. Only two Stage III brains were available, and their results merely suggested an intermediate pattern. The CTE analysis remains unreviewed conference research presented July 15 at the Alzheimer's Association International Conference in London.
The finding could matter because a reliable living-person test would help clarify symptoms and enroll appropriate participants in treatment trials. However, the researchers said confirmation in a much larger dataset is essential. One scientist involved in developing the assay works for Eisai, which is developing treatments targeting eMTBR-tau243, a relationship relevant when interpreting the early results.
Separate peer-reviewed work in Nature Medicine has shown that the plasma marker reflects Alzheimer's tau tangles, while another 2026 study found clinical symptom checklists alone correlated poorly with CTE found after death. Together, the evidence supports further biomarker research, not routine screening. The next steps are independent replication, larger and more diverse cohorts, and testing whether measurements can distinguish CTE from other tau-related diseases in living patients.
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