Scientists at Washington University identify blood biomarker eMTBR-tau243 that detects advanced CTE

Scientists at Washington University School of Medicine in St Louis reported on 14 November 2026 in the medical journal JAMA Neurology that they have identified a blood biomarker, eMTBR-tau243, which is elevated in an advanced form of chronic traumatic encephalopathy (CTE) in living people. The study found the protein fragment in blood and linked its levels with the severity of the disease.

CTE, caused by repeated trauma to the head, is currently diagnosable only after death by examination of brain tissue and is especially prevalent in collision and contact sports such as American football, rugby and football. The researchers reported that eMTBR-tau243 is elevated not only in Alzheimer’s disease but also in other brain diseases that share the same type of toxic protein buildup, including CTE. The paper appears in JAMA Neurology and lists Kanta Horie and Chihiro Sato among the co-authors.

When the team tested blood from 11 people whose CTE was confirmed at autopsy, they found eMTBR-tau243 levels were higher than in healthy people and rose with the severity of the brain disease. The authors report the test could distinguish people with advanced CTE from healthy people with high accuracy. The study also found the assay could not reliably identify early-stage CTE.

The researchers state the test has not yet been validated for diagnosing CTE. “We are potentially opening a new door for diagnosing and treating CTE in living patients,” said Kanta Horie, the co-senior author of the study in the medical journal JAMA Neurology.

“Our study shows that an Alzheimer’s disease biomarker can be applied to other tauopathies, including CTE,” the neuroscientist Chihiro Sato, who co-authored the study with Horie, said. “This is not going to be a standalone biomarker. But if someone has a history of repeated head injury, tests negative for Alzheimer’s and this biomarker comes up, it might be CTE.”

CTE remains a major focus across science and sport: in one recent study of nearly 400 NFL players whose brains were donated for examination after their deaths, 93.5% showed evidence of CTE. The article notes that more than 350 NFL players have been diagnosed with CTE after their deaths, including Mike Webster, Junior Seau and Frank Gifford.

Legal action is continuing from a number of living former rugby union and league players who have been diagnosed with Traumatic Encephalopathy Syndrome (TES), including the England World Cup winner Steve Thompson. The boxer Ricky Hatton also had a mild CTE diagnosis after his death, and earlier this year the Professional Footballers’ Association recommended that professionals should not head a ball more than 10 times a week in training sessions, and children under 12 not at all, as part of a CTE prevention protocol.

The authors said further large studies are required to confirm these findings; if those studies do so, clinicians could use such a blood test to monitor people at risk from CTE and to enable trials of drugs that could help the condition.