Boxers and MMA fighters may see their cognitive skills and brain structure recover after retirement

Brain damage suffered by athletes who take part in combat sports that subject them to repeated head trauma can be reversed after they step away from fighting, a new study finds.

Researchers at the Cleveland Clinic found that retired fighters tested better on verbal memory, executive functioning and motor speed two years after ending their careers. Their brain thickened as well, specifically in areas that control emotion, memory and executive functions.

The findings have wide reaching impacts for not only athletes, but for anyone who has suffered injury caused by repeated head-trauma. It shows that conditions like chronic traumatic encephalopathy (CTE) can be slowed, and potentially even reversed before they develop into more significant issues.

An estimated six percent of Americans are suffering from some form of CTE. Many are totally unaware as it is only usually associated with professional athletes even though repeated trauma from a person’s adolescence could be enough for it to develop. 

Researchers found that retired fighters (blue) often had better processing speeds, memories and reaction times at the end of the three year study period while active fighters (red) often scored the same or even worse over time

Many athletes who play combat sports like football, boxing, MMA, rugby and hockey are at risk of developing chronic traumatic encephalopathy (CTE), though it is estimated that around 6% of the total population suffers from the condition

Many athletes who play combat sports like football, boxing, MMA, rugby and hockey are at risk of developing chronic traumatic encephalopathy (CTE), though it is estimated that around 6% of the total population suffers from the condition

‘Repetitive hits to the head increase the risk of long-term neurologic conditions like chronic traumatic encephalopathy (CTE), cognitive and behavior problems and parkinsonism,’ Dr Aaron Ritter, a cognitive disease expert at the Cleveland Clinic, said in a statement.

‘However, we haven’t known what happens to people who have been fighting and then stop fighting. The good news is we saw some improvement in thinking and memory scores in these retired fighters.’

Researchers, who published their findings Wednesday in Neurology, gathered data from 90 boxers, mixed martial arts (MMA) fighters and martial artists.

Half of the sample group have not competed in two years, serving as the retirees in the study. The other half were active fighters.

Each fighter was matched with one in the other group who had a similar age, race, educational background and career fights taken part of during their career.


Chronic traumatic encephalopathy (CTE) is a degenerative brain disease that is caused by repeated hits to the head. Over time, these hits result in the accumulation of tau protein around the brain, which can lead to confusion, depression and eventually dementia.

There have been several retired football players who have come forward with brain diseases, many of whom attribute their condition to the game. 

More than 1,800 former athletes and military veterans have pledged to donate their brains to the Concussion Legacy Foundation for CTE research.

CTE was usually associated with boxing before former NFL players began revealing their conditions. 

Several notable players who committed suicide were posthumously diagnosed with the disease, such as Junior Seau and Aaron Hernandez. 

While often connected to concussions, many researchers like Lee E. Goldstein, MD, PhD, an associate professor at Boston University, now believe sub-concussive hits also play a major part in CTE. 

‘Over the course of an NFL season, the overwhelming majority of hits are sub-concussive,’ Goldstein told ‘I’m not saying [the NFL is] wrong for focusing on concussions. But I am saying they’re mis-prioritizing.’ 

Over the course of three years, all 90 participants regularly completed cognitive tests to determine how well their brain was functioning, and at what rate was it improving or deteriorating.

Retired fighters showed improvements on their cognitive scores over the period, implying that their brain was recovering in some way from previous injuries.

They also had better memory, reaction time and mental processing speed by the end of the study when compared to the start.

Meanwhile, no positive change was found among active fighters, while many even declined in some of these facets over the three year period.

Researchers also gathered levels of neurofilament light chain, a blood biomarker that is known to be able to predict future cognitive decline.

Retired fighters had decreased levels by the end of the study, implying that their future risk of further cognitive decline was actually decreasing.

This was not the case for active fighters, whose biomarker levels stayed consistent through the period.

The research team also measured mass and thickness of 68 different regions of the brain. For 54 of those regions, retired fighters showed slight increases in mass while the opposite was true for those that were still entering the ring.

‘The results of this study suggest a recovery of cognitive functioning in fighters who are no longer exposed to repetitive hits to the head,’ Ritter added. 

‘Future research is needed to determine if there is a time in a fighter’s career where recovery is less likely to happen or to identify factors that might indicate greater risk for developing a neurodegenerative condition.’ 

While a study of only 90 is not large enough to make widescale conclusions, the findings spell out hope for the millions of people suffering from CTE.

The condition has risen to prominence in recent years, primarily because of its association with former NFL players.

A study published in 2017 found that 99 percent of former NFL players who believed they were suffering cognitive symptoms before their death were suffering from CTE.

People who play other combat sports like hockey, rugby or combat sports could be at a significant risk as well.

While it is most often associated with professional athletes, anyone who has suffered repeated head trauma at any point in life – like a person who play sports recreationally in their youth – is at risk. 

A 2019 study found that six percent of Americans are likely suffering from CTE.

The condition can cause severe memory loss, mood swings, confusion and other cognitive problems.

In most serious cases, a person suffering from CTE will have their condition develop into Parkinson’s.