A new study of a blood biomarker linked to chronic traumatic encephalopathy (CTE) offers a preliminary research clue, not a diagnostic test. Researchers found higher levels of the protein fragment eMTBR-tau243 in people with advanced CTE, but the marker could not reliably identify early-stage disease and has not been validated for clinical diagnosis.

What the CTE biomarker study found

The study, published Nov. 13 in JAMA, examined eMTBR-tau243 in blood and cerebrospinal-fluid samples from a broader group of 229 participants. The researchers reported elevated levels in several conditions involving mixed forms of tau pathology, including late-stage CTE. In the CTE portion of the blood analysis, samples from 11 people whose disease had been confirmed after death showed higher levels than samples from healthy controls.

The signal rose with disease severity in those samples, but it did not reliably flag early CTE. An outside neuropathologist interviewed by The Associated Press called the result very preliminary and said much larger studies are needed to establish whether the connection holds.

Why the finding is not a CTE blood test

CTE is currently confirmed by examining brain tissue after death. The study does not change that, and it does not show that people can use this blood marker to determine whether they have CTE. The protein fragment is also associated with Alzheimer’s disease and other tau-related conditions, so the marker by itself cannot distinguish CTE from those diseases.

The researchers say larger validation studies would be needed before the method could be considered for clinical use. The reported samples were tied to diagnoses established through brain or genetic pathology, rather than a prospective test of people seeking a CTE diagnosis while alive.

What researchers need to establish next

Further work would need to test the marker in larger groups, including people with early disease and people with similar symptoms from other causes. That would help determine whether the signal can meaningfully separate CTE from Alzheimer’s and other conditions, and whether it adds useful information beyond existing assessments.

There is also a disclosed commercial connection: Washington University said it licensed the technology for measuring eMTBR-tau243 in blood to C2N Diagnostics, and noted that some researchers may receive income tied to that licensed technology. The study’s authors also reported financial relationships. Those disclosures do not determine whether the results are valid, but they are relevant context as the findings are independently tested.

Sources

The Associated Press: Preliminary study finds a clue in the quest to help diagnose CTE in the living

JAMA: Fluid eMTBR-tau243 as a Biomarker of Mixed 3-Repeat and 4-Repeat Tau Pathology

WashU Medicine: Progress toward a blood test for CTE