Doctors hope new research will help them tell which professional fighters are at the highest risk for incurring permanent brain damage.

The groundbreaking clinical study at the Lou Ruvo Center for Brain Health in Las Vegas will follow over 400 boxers and mixed martial arts (MMA) fighters from around the world for up to five years.

“The focus of the study is the long-term consequences of getting shots to the head over and over again,” Dr. Charles Bernick, of the Cleveland Clinic's Lou Ruvo Center for Brain Health in Las Vegas, told FoxNews.com.

Doctors will examine the fighters up to three times a year. They’ll receive treatment and scans to determine any current medical conditions, and will also assess how each participant's health might worsen or improve.

Former heavyweight boxer Brett Rather is one of the study's participants. He was a champion fighter for 13 years and a reserve athlete in the 2012 Olympic Games in London. Rather has sustained numerous injuries throughout his career as a boxer.

“I started breathing out of one nostril,” Rather told FoxNews.com. “I had to get Lasik on one of my eyes twice because I started going a little bit blind in one of them.”

Despite the side effects, Rather continued fighting until a devastating blow knocked him unconscious.

“I took just a quick, flash [knockout], and you only see me for a split second on the ground, but in my head, I feel like I was lost for 20 seconds,” he said.

By joining the study, Rather is now hoping to reverse some of the damage he may have suffered.

Professional fighters are likely to experience numerous concussions over the course of their career, and often suffer from behavioral problems such as forgetfulness and mood swings, which is what doctors will primarily be researching, Bernick explained.

“What we’re trying to do is be able to tell an individual if they’re at risk [for brain damage] by identifying the risk factors,” Bernick said. “But, also being able to detect any early changes that could be a warning sign, and also let athletes know about this so that they can make decisions themselves.”

Frank Slaughter has trained dozens of professional fighters over the course of his career. He’s encouraging all of his clients to get involved in the study, telling them their health is more important than any prize.

“I’d be the first one to say to this man, 'You have to stop fighting it’s not beneficial to your health,'” Slaughter told FoxNews.com, referring to one of his most successful fighters.

Rather wishes someone offered him the same advice years ago.

“Nobody ever talks about that, you know? You get knocked out, you wake up, throw up in the garbage can, you go home.” he said. “I might’ve taken a hit that might affect me five years from now.”