For the past six years, the middleweight boxer Austin ‘No Doubt’ Trout has traveled annually to the Cleveland Clinic for a battery of tests—MRIs, memory and balance assessments, and bloodwork—all conducted as part of the Professional Athletes Brain Health Study. Trout, who is one of hundreds of active and retired professional fighters enrolled in the study, participated to help his fellow fighters, and because he wants to understand the impact a professional boxing career has had on his brain health and his risk of developing chronic traumatic encephalopathy (CTE), a neurodegenerative disorder caused by multiple concussions or blows to the head.
CTE develops over time, with symptoms—memory issues, declines in cognitive functioning and behavioral changes—usually starting in mid-life. It can develop in athletes who compete in contact sports, such as football, ice hockey, boxing, and mixed martial arts. It can also arise in people with a history of repeat head injuries, such as military personnel and victims of domestic violence.
CTE can only be diagnosed after death by conducting an autopsy, which creates barriers for studying how it develops and what treatments might be effective.
Now, thanks to the contributions of Trout and his fellow fighters, researchers are starting to uncover some of the early signs and symptoms that are likely associated with CTE. In a recent study, published in the journal Neurology, researchers looked at a cohort of 130 professional fighters, including active and recently retired boxers and mixed martial artists.
For Trout, who was raised by a single mother in Las Cruces, New Mexico, boxing has been a lifeline. In his early days, the sport offered him structure, community, and purpose, during a time when he desperately needed it. “I didn’t care about the cops, I didn’t care about my teachers, but I did care about not letting down my mom, and later on, my coach,” says Trout, age 37. “I needed that structure in my life.”
As Trout matured as a an athlete, eventually becoming professional, boxing became a career. It allowed him to support his family and advance in the field. He won the World Boxing Association light middleweight title in 2011 and has competed against some of the biggest names in boxing, such as Saul ‘Canelo’ Alvarez, Miguel Cotto, and Jermell Charlo.
However, as Trout is keenly aware, boxing often extracts a high collateral damage that manifests later in life, one that is poorly understood. “The story with fighters is always that they end up punch-drunk, broke, and begging,” Trout says. “I was happy to be part of something that was very proactive for fighters.”
Over a period of six years, researchers tracked changes in fighters’ cognitive functioning and brain structure. Of the 130 professional participants, 50 of them met the criteria for traumatic encephalopathy syndrome, or TES, which is the proposed clinical presentation of suspected CTE. The athletes who met the criteria for TES showed a pattern of declining cognitive skills and changes in brain structure—which included some areas of the brain shrinking, other parts of the brain swelling.
“What’s really novel about this study is that it is showing some progressive changes in the brain over a period of time,” says Michael Alosco, a neurology researcher at Boston University’s CTE Center, who was not involved with the study. In contrast to previous studies, which looked at retired athletes, researchers carried out detailed measurements on active fighters, during a period of time when they were at an elevated risk for developing CTE. “It’s an exciting study.”
For fighters such as Trout, these studies can help them better understand their relative risks for developing neurodegenerative disorders such as CTE.
The precursor to CTE
In 2021, a group of researchers proposed a set of clinical symptoms that are thought to be associated with traumatic encephalopathy syndrome. As of right now, TES is only used in research. “No clinician should be diagnosing their patients with TES,” says Kristen Dams-O'Connor, a neuropsychologist and the director of the Brain Injury Research Center of Mount Sinai, who was not involved with the study. “These are provisional research criteria, for use by researchers.”
The symptoms that characterize TES are thought to be harbingers of CTE. Ultimately, researchers hope that by identifying patients with TES, they’ll be able to definitively diagnose and treat patients who are developing CTE. “The hope is that over time, we will be able to make further modifications to these criteria, to make it more precise and more accurate,” says Charles Bernick, a neurologist at Cleveland Clinic, and one of the authors of the paper.
As Dams-O'Connor points out, many of these neurodegenerative disorders look alike, but will likely require different treatment options. In order to be able to develop effective therapies for CTE, researchers will first have to identify which patients have CTE, versus some other neurodegenerative disorder. One of the first steps in this process is identifying people who are likely to be developing CTE, with a goal of tracking their progression over time, in order to determine what differentiates one disorder from another.
Similar pattern of brain changes
For 50 of the 130 professional fighters, they showed a similar pattern of brain changes over time. The changes included variations in the volume of certain brain regions and declining cognitive skills. For the changes in brain volume, fighters who met the criteria for TES showed similar patterns in different regions of the brain. These patterns can help researchers define what CTE looks like in its earlier stages, and predict which fighters are most at risk. “It’s a surrogate of a neurodegenerative process,” Bernick says.
Although the fighters who meet the criteria for TES may not necessarily be developing CTE, says Kyle Womack, a neurologist at Washington University in St. Louis, it is highly likely that they are developing some form of neurodegenerative disorder.
The goal is to identify a biomarker that can indicate that the developing issues are CTE, rather than a similar disorder, before any symptoms appear. “The emergence of symptoms are the tip of the iceberg of what has been going on over time,” says Womack, who was not part of the study. “If symptoms have already developed, then it may be too late.”
Further studies needed
When the Professional Athletes Brain Health Study first started, it was restricted to professional fighters only. Now, as the study progressed over the past decade, it has expanded to include other professional athletes who compete in contact sports, such as motorsports and rodeo. “In terms of the pattern of head impacts, we don’t know if there is a difference in long-term outcomes,” Bernick says. It may be that professional football players are more susceptible to one type of neurogenerative disorder, compared to professional boxers or mixed martial artists.
For Trout, his six years of testing has showed no evidence of declining cognitive skills, or changes in brain volume, which he acknowledges makes him luckier than most. In the meantime, he’s switched over to bare-knuckle boxing, which has a lower risk of head injury. He’s also scheduled to go back to the Cleveland Clinic in the fall, to continue participating in the study. “The reason I’ve been able to compete at this level, at my age, is because of my defense,” Trout says. “A lot of boxers will take a hit to land a hit, but I’m the opposite, I’m going to hit you, so you don’t hit me.”