For former footballers, boxers and combat veterans, chronic traumatic encephalopathy has long been a diagnosis that can only be confirmed once they have died. Doctors can only see the tell-tale damage, caused by years of knocks to the skull, when examining brain tissue post mortem. Scientists at WashU Medicine in Missouri now report in JAMA that a blood marker may flag advanced cases while patients are still alive.
The marker is a fragment of tau, a protein that normally props up the internal skeleton of nerve cells but can clump together and damage the brain. Researchers led by Kanta Horie and Chihiro Sato had developed the measurement, called eMTBR-tau243, to track Alzheimer’s disease. While testing it, they noticed one person with a high reading but no Alzheimer’s changes in the brain. Going back through the records, they found that this patient had severe CTE.
Next, the researchers turned to eleven deceased patients with an autopsy-proven diagnosis and checked samples taken during their lifetimes. Their levels sat well above those of healthy volunteers and climbed as the disease worsened. Across the full study of 229 participants drawn from several US biobanks, the test separated late-stage CTE from healthy controls with high accuracy, though it struggled to pick up early stages.
The scientists are careful not to oversell the result. Because the same fragment rises much more sharply in Alzheimer’s, and the two diseases often occur together, the marker cannot tell them apart on its own. “This is not going to be a standalone biomarker,” Sato said. It could help, the team suggests, in someone with a long history of head injuries who tests negative for Alzheimer’s. Bigger studies are still required.
Even a partial tool would matter. Drug developers are working on possible treatments, but without a measurable signal it is hard to run trials or see whether a therapy works. Rights to the method sit with C2N Diagnostics, a company spun out of the university whose Alzheimer’s test has already won approval from US regulators.
