Boxers and mixed martial arts fighters may have markers of long-term brain injury in their blood, a US medical conference has heard. Researchers studied blood samples from 291 active professional fighters (128 boxers and 163 mixed martial arts), 44 retired fighters (38 boxers, 6 mixed martial arts), and 103 non-fighters. They measured two blood plasma proteins that are known biological markers of brain injuries: Neurofilament light chain (NFL) and Tau.
In active fighters the protein levels were 40% higher than in non-fighters or retired fighters. NFL levels, but not tau, were higher depending on how much fighting the participants said they’d done in the fortnight before testing. The results were not affected by age or ethnic backgrounds. However, those with higher NFL levels also did worse in computer-based tests of brain processing speed.