A possible blood-test lead for a condition diagnosed only after death
Researchers have reported an early clue that could eventually help doctors evaluate chronic traumatic encephalopathy, or CTE, in living people. The finding centers on eMTBR-tau243, a fragment of the protein tau that researchers had been studying as a possible marker of Alzheimer’s-related tau tangles.
CTE is associated with repeated blows to the head, including concussions and other brain trauma. At present, clinicians can assess symptoms and a person’s history, but they cannot definitively diagnose CTE while a patient is alive. Confirmation requires examination of brain tissue after death. That gap makes it difficult to distinguish possible CTE from other disorders that can also involve memory problems, mood changes, or behavioral symptoms.
The new result does not change that clinical reality. It is a preliminary signal from a small set of samples, and researchers caution that it must be replicated at much larger scale. Still, it offers a more specific direction for research into a long-standing diagnostic challenge.
An unexpected result in autopsy research
Scientists at Washington University in St. Louis were examining autopsy samples while studying eMTBR-tau243 in the context of Alzheimer’s disease. Tau normally helps support neurons. In Alzheimer’s disease, however, abnormal tau can accumulate and form tangles inside nerve cells.
During that work, the team encountered an unusual case: a person with high levels of the biomarker whose records did not indicate Alzheimer’s disease, but did indicate advanced CTE. That observation prompted the researchers to look further across a larger collection of autopsied brain and other samples.
They ultimately examined stored blood from 11 people classified as having CTE. Compared with healthy people, those with advanced CTE had higher levels of eMTBR-tau243, according to study co-author Chihiro Sato, an assistant professor of neurology at Washington University.
The result was not equally useful across the condition’s progression. The biomarker could not reliably identify early-stage CTE. That limitation is central: a clinically useful test would need to demonstrate clear performance across relevant patient groups, including people with early disease and those with other conditions that affect tau.
Why a tau signal is difficult to interpret
CTE research faces a basic biological complication. Abnormal tau is not unique to CTE. It is found in several brain diseases, and more than one tau-related condition can occur in older adults. That overlap makes it difficult to determine what a given blood signal means for an individual patient.
Dr. Rudolph Castellani, a neuropathologist at Northwestern University who was not involved in the research, described the finding as interesting but very preliminary. He said much larger studies will be needed to determine whether there is a meaningful connection between the biomarker and CTE.
That caution is especially important because a blood biomarker can be valuable without being a stand-alone diagnosis. Future work would need to establish whether eMTBR-tau243 adds useful information alongside symptoms, exposure history, neurological testing, imaging, and evaluation for other diseases. Researchers would also need to understand how the marker behaves in people with head-trauma histories who do not have CTE.
What the finding does—and does not—mean
The study points to a research avenue rather than an available clinical test. It does not establish that a blood draw can diagnose CTE, and it does not show that the marker can detect the condition early. Nor does it resolve how to distinguish CTE from other tau-related disorders in an individual patient.
Its importance is that it identifies a measurable fluid marker that was higher in a small group with advanced CTE. If follow-up studies confirm the association and clarify its limits, researchers may have a tool for studying CTE in people during life rather than relying solely on postmortem examination.
That could improve research as much as diagnosis. A validated biomarker could help scientists group participants for studies, track biological changes over time, and evaluate whether potential treatments affect disease-related processes. Those are future possibilities, not conclusions from this initial report.
Next steps
Sato emphasized that substantially more research is needed. The next studies will need larger and more diverse participant groups, comparison populations with other neurological diseases, and evidence that blood levels correspond reliably to CTE-related pathology. Researchers will also need to test whether the signal can be detected at stages when clinical assessment would be most useful.
For now, the result is best understood as a clue from autopsy-linked and stored-sample research. It reinforces the possibility that tau biology may offer a route toward better tools for CTE, while underscoring how far the field remains from a validated diagnosis in the living.
The findings were published in JAMA and presented at a scientific meeting in Japan.
This article is based on reporting by Medical Xpress. Read the original article.
Originally published on medicalxpress.com
