A neuroimaging study of retired professional fighters has revealed that those with better win-loss ratios tend to exhibit greater impulsiveness and slower cognitive processing speeds. Furthermore, these individuals typically have reduced volumes in several brain regions. The paper was published in the Journal of Neuropsychiatry and Clinical Neurosciences.
High-impact sports, such as football, rugby, and boxing, pose a significant risk of traumatic head injuries for professional athletes due to the intense physical contact and collisions involved. These injuries are most often concussions, a type of traumatic brain injury that happens when a bump, blow, or a jolt to the head, or a hit to the body cause the brain to move rapidly inside the skull, leading to temporary disruption of normal brain function.
Repeated concussions or severe traumatic brain injuries can lead to chronic conditions, such as chronic traumatic encephalopathy, a degenerative brain disorder with symptoms that include memory loss, confusion, impaired judgment, and mood swings. On the biochemical level, this condition involves widespread accumulation of a protein called hyperphosphorylated tau protein in the brain. This accumulation disrupts the function of neurons and can ultimately contribute to their death, leading to cognitive decline, memory loss, and various neurological symptoms.
In their new study, Barry R. Bryant and his colleagues sought to explore the correlation between the win-loss ratios of professional mixed martial artists (MMA) and boxers and their neuropsychiatric symptoms, brain volumes in specific areas, and cognitive functioning. They hypothesized that retired fighters with poorer fight records—those who endured more physical beatings during their careers—would show worse neuropsychiatric symptoms and indicators of brain health.
The research team analyzed data from the Professional Fighters Brain and Health Study, an ongoing longitudinal study assessing neuropsychiatric symptoms, cognitive function, and regional brain volume among professional boxers and MMA fighters. This particular analysis involved data from 212 professional fighters, of which 73% were active and 27% were retired.
Bryant and his colleagues analyzed data on fighters’ depressive symptoms (the Patients Health Questionnaire-9), impulsiveness (the Barratt Impulsiveness Scale), and cognitive performance (the CNS Vital Signs Neurocognitive battery and several other tests). Fighters underwent magnetic resonance imaging (MRI) of their brains, and the researchers calculated each fighter’s win-loss ratio (wins plus half of the draws divided by the total number of fights).
The results indicated that fighters with better win-loss ratios had smaller volumes in the left thalamus and both the left and right hippocampi. Among retired fighters, those with better win-loss ratios throughout their careers showed reduced volumes in several brain regions, including the subcortical gray matter, anterior corpus callosum, both hippocampi, both amygdalae, and the left thalamus. Active fighters with better win-loss ratios had a smaller left amygdala volume. No regions were found where fighters with worse win-loss ratios had smaller volumes.
Retired fighters with better win-loss ratios also displayed greater impulsiveness and slower cognitive processing speeds, though depressive symptoms did not correlate with win-loss ratios.
The study authors concluded, “Our results suggest that among retired fighters, a better fight record was associated with greater impulsiveness, slower processing speed, and smaller brain volume in multiple brain regions. In addition, our findings suggest that even successful fighters experience adverse effects on brain health.”
The study sheds light on the links between cognitive ability and brain characteristics of professional fighters. However, it should be noted that the study design does not allow any cause-and-effect inferences to be drawn from the data. While it is possible that specificities of brains of retired fighters are indeed a consequence of injuries suffered during fights, it might also be the case that their psychological and neurological characteristics made them more successful fighters or that both their brain characteristics and fighting success were determined by other factors.
The paper, “Association of Win-Loss Record With Neuropsychiatric Symptoms and Brain Health Among Professional Fighters,” was authored by Barry R. Bryant, Aaron I. Esagoff, Lisa Young, Natalia Kosyakova, Michael Bray, Lisa N. Richey, Varun Vohra, Guogen Shan, Andrea L.C. Schneider, Matthew E. Peters, Charles B. Bernick, and Bharat R. Narapareddy.