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Study shows significant effects of MMA and boxing on the human brain

A new study by the American Academy of Neurology shows fairly significant volume decreases in portions of the brains of boxers and mixed martial artists.

Kevork Djansezian

A medical paper was put out by the American Academy of Neurology titled "Structural and Functional Brain Changes in Boxers and Mixed Martial Arts Fighters Are Correlated with Fight Exposure." The paper covered a study of 239 professional fighters, comparing their brain function, age, career length and number of bouts.

The findings, while not surprising, do confirm what reasonable people would presume about a sport where you get hit in the head. Mainly, that it's not all that great for your brain.

Here's a bit from the Med Page Today article on the paper:

Among 104 boxers and 135 mixed-martial arts (MMA) competitors -- many of them "cage fighters" -- the number of years of pro fighting correlated significantly with reduced volume in the caudate and amygdala, and strong trends were seen toward smaller volumes in the thalamus and putamen, reported Sarah Banks, PhD, of the Cleveland Clinic's Lou Ruvo Center for Brain Health in Las Vegas.

Resting state functional MRI scans also indicated a correlation between lower connectivity between regions and the amount of fighting experience, she told attendees at the American Academy of Neurology's annual meeting.


The only numerical findings Banks reported were on the relationship between career initiation and length and volumes of particular brain regions of interest: caudate, putamen, thalamus, amygdala, and hippocampus. Up to about year 5 of fight experience, volumes of all these regions did not vary.

With experience beyond year 5, however, volumes declined -- most sharply for the caudate. In that region, volumes were 10% lower in participants with 15 years of experience compared with those fighting for 5 years or less (P<0.001).

Volumes were lower by about 5% for the amygdala and putamen (P=0.036 and 0.067, respectively).

There was a lesser trend toward smaller volumes with experience in the thalamus (P=0.092) and no hint of a relationship in the hippocampus.

Caudate volumes and years of fighting experience were more strongly related in participants who said they began fighting in earnest at age 15 or younger, Banks said. In that subgroup, caudate volumes were smaller by 0.37% for each bout reported by participants. In contrast, the reduction was only 0.10% per bout for participants who said they began fighting after age 15.

Participants with relatively longer careers and higher frequency of fights also tended to show reduced connectivity between the basal ganglia and other brain regions, she said.

She pointed out that the basal ganglia has been identified in previous studies of chronic head injury in athletes as a locus for abnormalities. In particular, much of the CTE pathology seems to be centered there.

In short, fighting for a long time and fighting frequently -- especially when starting your career at age 15 -- appears associated with volume reduction in certain areas of the brain and reduced connectivity between the basal ganglia and other regions of the brain.

So, as stated earlier, it's not exactly news one wouldn't expect. But, it is important to accept that this is a reality of the fight game. There's still resistance to accepting that MMA carries long-term brain trauma risk, a remnant of the days when the "safer than boxing" push became more of a "completely safe" narrative.

No one is saying that boxing or MMA should be done away with because of these risks. But it would be a very good idea if trainers and fighters look at studies like this and take away from it a need to not run camps and gyms that frequently duplicate full on fight situations in sparring. Sparring is necessary, but things like the "legendary Chute Boxe wars" are not. And there's also a need to give guys frequent time off from head contact and sit them out completely when they get "buzzed" or "have their bell rung."