The Relationship Between Fighting Style, Cognition, and Regional Brain Volume in Professional Combatants: A Preliminary Examination Using Brief Neurocognitive Measures.

Objective: Repetitive head impacts (RHIs) in combat sports are associated with cognitive decline and brain volume reduction. While fighting style differences between boxers, mixed martial artists (MMAs), and martial artists (MAs) have resulted in a broader spectrum of injury, the effects of RHIs on MAs relative to other fighters have not yet been explored. This study aimed to determine a differential effect of fighting style on cognition and brain.

Setting: A large outpatient medical center specializing in neurological care.

Participants, Design, And Main Measures: In total, 40 MAs, 188 boxers, and 279 MMAs were compared on baseline measures of subcortical regional brain volumes, after controlling for total brain volumes, and cognitive performance.

Results: Significant differences between MAs, MMAs, and boxers were observed in subcortical brain structure volumes and cognitive measures. MMAs and MAs consistently had larger volumes and higher scores than boxers. Fighting style significantly moderated the relationship between the number of professional fights and the volumes of various subcortical brain structures and performance on a measure of processing speed at baseline.

Conclusions: Differences in RHIs across fighting styles may be of clinical significance. Exploring changes over time within the MA, boxer, and MMA cohorts may provide insight into longer-term discrepancies in subcortical regional brain volumes and cognitive functioning across fighting styles.