Cleveland Clinic looking at biomarkers in blood as potential indicators of long-term brain damage

The Cleveland Clinic Lou Ruvo Center for Brain Health in Las Vegas. AP Photo/Isaac Brekken

LAS VEGAS -- Researchers at Cleveland Clinic Lou Ruvo Center for Brain Health have identified two biomarkers that might greatly assist in assessing a patient's risk for accumulative brain damage.

According to findings from the Professional Fighters Brain Health Study -- which began in 2011 and has drawn funding from the top boxing and MMA promotions in the U.S. -- a group of athletes has shown increased levels in the brain protein tau and those with increased levels show a 7 percent decrease in thalamus size.

A second biomarker, neurofilament light chain (NfL), proved to be 40 percent higher in active fighters compared with retired ones.

Neither is new to the science world, but this is the first time their levels have been monitored over time in combat sports athletes. Both are released into the bloodstream when nerve fibers in the brain suffer damage. Increased levels of tau have been linked to increased risk for chronic traumatic encephalopathy (CTE).

According to Dr. Charles Bernick, the study's lead researcher, these findings could be an initial step toward developing a better way to assess individual brain health.

"Everybody is interested in finding a simple way to determine whether or not a person has suffered a brain injury," Bernick told ESPN. "What we're speculating is that measuring levels of tau over the course of someone's career may be a way to see accumulating injury. The next step is to continue MRI scans for those with increased levels of tau and linking those to recognizable injury."

Bernick has seen more than 600 athletes come through the study, the majority of them active. One of the most consistent questions he is asked is, "When should I stop doing this for a living?"

Awareness of degenerative brain disease has never been higher in sports. Last month, the JAMA medical journal published a study that found 99 percent of deceased NFL players' brains donated to scientific research showed signs of CTE. That study promises to be at the source of many discussions heading into the 2017 season.

Of course, boxers and mixed martial artists face the same reality. Repeated blows to the head are a health risk, but there is very little physical data, beyond MRI scans, for them to base their career choices on.

One of the main purposes of Bernick's study is to finally identify and provide that type of data to athletes.

"At the moment, they're asking themselves if they have symptoms or if they've lost any skills -- that's been the traditional way for people to make decisions," Bernick said. "What you want to do is give them a better sense of what's happening to them individually, not as a group. 'This is what's happening in your brain, and these are the risks.'"

While monitoring rising levels of tau might prove useful long term, flagging increased levels of NfL might offer practical, short-term uses.

Higher levels of NfL were directly linked to self-reported increases in sparring. Obviously, that remains an important fixture in fight preparations, but those increases in NfL were also linked to slower response times in computerized tests.

If it's further proved that these NfL readings indicate slower reaction times, perhaps that's information that would have real implications on training methods.

"If you're running tests in an effort to see if someone's injured, people don't like that," Bernick said. "But if you're coming to them from a performance standpoint, maybe this would change how some of them train.

"If we can show fighters, using these biological tools, that they're going into a fight at a disadvantage, that's something they may buy into."