As part of a study of brain injury among boxers and mixed martial arts (MMA) fighters, researchers found high levels of two biological markers of brain injury—a brain protein called neurofilament light chain, as well as tau—in their blood.

“This study is part of a larger study to detect not just individual concussions but permanent brain injury overall at its earliest stages and to determine which fighters are at greatest risk of long-term complications,” said study author Charles Bernick, MD, of the Cleveland Clinic Lou Ruvo Center for Brain Health in Las Vegas and amember of the American Academy of Neurology, in a media release.

“Our study looked at data over a 5-year period and found elevated levels of two brain injury markers in the blood; now the question is whether they may signify permanent traumatic brain injury with long-term consequences.”

In their study, presented recently at the American Academy of Neurology’s Sports Concussion Conference in Jacksonville, Fla, the researchers took blood samples from 291 active professional fighters with an average age of 30, 44 retired fighters with an average age of 45, and 103 non-fighters with an average age of 30. The blood samples were then tested for levels of both proteins.

Researchers found that active professional fighters had higher levels of both proteins compared to retired fighters or non-fighters. For example, they found that levels of neurofilament light chain were 40% higher in active boxers than in non-fighters. They also found that the more a fighter sparred in the 2 weeks before the blood samples were taken, the higher the levels of neurofilament light chain in their blood.

Neither age, ethnicity, or number of professional fights among the active fighters were linked to levels of either protein, the release adds.

While neurofilament light chain protein was higher in active fighters at the start of the study, the levels did not increase significantly during the study period.

However, per the release, among the fighters who had increasing levels of tau over time, there was a 7% decline in the volume of their thalamus.

Finally, the study found that fighters with higher levels of neurofilament light chain protein did not do as well on computerized tests that measure the brain’s processing speed as the retired fighters and non-fighters.

“Our study found that higher levels of both proteins may be associated with repetitive head trauma,” Bernick states in the release. “However, neurofilament light may be more sensitive to acute traumatic brain injury whereas tau may be a better measurement of cumulative damage over time. More research needs to be done to see how these may be used to monitor traumatic brain injury and the neurological consequences over time.”

A limitation of the study was the difference in the average age of active and retired fighters, according to the release.

This study is part of the ongoing Professional Fighters Brain Health Study.

[Source(s): American Academy of Neurology, Science Daily, PR Newswire]