CTE blood-marker study offers early evidence, but diagnostic test remains unvalidated

Researchers have identified a blood marker that could help efforts to detect chronic traumatic encephalopathy in living people, according to a report by The Guardian. The findings concern a condition linked to repeated head trauma and of particular concern in contact sports, including rugby and American football. The test remains unvalidated for diagnosing CTE and did not reliably identify early-stage disease.

The study, published in JAMA Neurology, was conducted by scientists at Washington University School of Medicine in St Louis. It examined a protein fragment called eMTBR-tau243, which is elevated in Alzheimer's disease and other conditions involving a similar accumulation of toxic proteins. Researchers tested blood from 11 people whose CTE diagnoses were subsequently confirmed through examination of brain tissue after death.

Levels of the marker were higher in those participants than in healthy people, and increased with the severity of their disease. The researchers reported that the test could distinguish advanced CTE from healthy cases with high accuracy. However, its inability to reliably detect early cases is an important limitation, alongside the need to confirm the findings in larger studies.

Co-author Chihiro Sato told The Guardian that the marker would not be sufficient on its own. A history of repeated head injuries and testing to exclude Alzheimer's would also matter when interpreting an elevated result. CTE currently requires examination of brain tissue after death for diagnosis, so the study does not establish a replacement diagnostic test that can already be used in living patients.

The researchers said that, if larger studies support their findings, a blood test could eventually help clinicians monitor people at risk and support trials of potential treatments. Co-senior author Kanta Horie described the research as a possible route towards diagnosis and treatment during life. Those potential applications remain conditional rather than demonstrated outcomes of the small study.

The findings arrive amid continuing concern over head injuries in sport. The Guardian reported that former rugby union and rugby league players diagnosed with Traumatic Encephalopathy Syndrome remain involved in legal action, including England World Cup winner Steve Thompson. The report also noted that more than 350 former NFL players have received CTE diagnoses after death, underlining the sporting context for research into detecting the condition earlier.