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.

Concussion reporting and perceived knowledge of professional fighters.

Objective: For concussions to be effectively managed in sports, they need to be correctly identified and reported. The extent to which professional athletes correctly recognize concussions, and their willingness to report symptoms, is not yet well understood. Given the risk of head injuries leading to concussions across combat sports, insight into professional fighters' knowledge and reporting of concussive symptoms is essential to improve concussion management. Methods: To investigate understanding and reporting patterns of concussions sustained while training or competing, 257 fighters completed a self-report questionnaire assessing self-perception of concussion knowledge, trust of ringside medical providers, and reported number of previous head injuries. Fighting history, including number of knockouts, was obtained from self-report (amateur) and published (professional) records. Results: Significant gaps in fighters' perceived knowledge of concussion symptoms and long-term effects of multiple concussions emerged. Approximately 40% of fighters reported returning to training or competition the same day a head injury was sustained, while 21% of fighters endorsed concealing symptoms of head injury from medical providers and coaches. Conclusions: Confusion surrounding terms used to describe head injuries amongst fighters (e.g., concussions, knockouts), coupled with limited understanding of concussive symptoms and a desire to return to competition, likely contributes to significant underreporting of symptoms.

Multimodal MR Imaging Signatures of Cognitive Impairment in Active Professional Fighters.

Purpose To investigate whether combining multiple magnetic resonance (MR) imaging modalities such as T1-weighted and diffusion-weighted MR imaging could reveal imaging biomarkers associated with cognition in active professional fighters. Materials and Methods Active professional fighters (n = 297; 24 women and 273 men) were recruited at one center. Sixty-two fighters (six women and 56 men) returned for a follow-up examination. Only men were included in the main analysis of the study. On the basis of computerized testing, fighters were separated into the cognitively impaired and nonimpaired groups on the basis of computerized testing. T1-weighted and diffusion-weighted imaging were performed, and volume and cortical thickness, along with diffusion-derived metrics of 20 major white matter tracts were extracted for every subject. A classifier was designed to identify imaging biomarkers related to cognitive impairment and was tested in the follow-up dataset. Results The classifier allowed identification of seven imaging biomarkers related to cognitive impairment in the cohort of active professional fighters. Areas under the curve of 0.76 and 0.69 were obtained at baseline and at follow-up, respectively, with the optimized classifier. The number of years of fighting had a significant (P = 8.8 × 10-7) negative association with fractional anisotropy of the forceps major (effect size [d] = 0.34) and the inferior longitudinal fasciculus (P = .03; d = 0.17). A significant difference was observed between the impaired and nonimpaired groups in the association of fractional anisotropy in the forceps major with number of fights (P = .03, d = 0.38) and years of fighting (P = 6 × 10-8, d = 0.63). Fractional anisotropy of the inferior longitudinal fasciculus was positively associated with psychomotor speed (P = .04, d = 0.16) in nonimpaired fighters but no association was observed in impaired fighters. Conclusion Without enforcement of any a priori assumptions on the MR imaging-derived measurements and with a multivariate approach, the study revealed a set of seven imaging biomarkers that were associated with cognition in active male professional fighters. © RSNA, 2017 Online supplemental material is available for this article.

Lack of Influence of Apolipoprotein E Status on Cognition or Brain Structure in Professional Fighters.

The role of the apolipoprotein e4 allele in moderating cognitive and neuroanatomical degeneration following repeated traumatic brain injury is controversial. Here we sought to establish the presence or absence of such a moderating relationship in a prospective study of active and retired boxers and mixed martial arts fighters. Fighters (n = 193) underwent cognitive evaluations, interviews regarding fight history, MRI of the brain, and genetic testing. We used a series of moderator analyses to test for any relationship of apolipoprotein genotype on structural volumes of brain regions previously established to be smaller in those with the most fight exposure, and on cognitive abilities also established to be sensitive to fight exposure. No moderating relationship was detected in any of the analyses. The results of this study suggest that there is no impact of apolipoprotein genotype on the apparent negative association between exposure to professional fighting and brain structure volume or aspects of cognition.

Repeated head trauma is associated with smaller thalamic volumes and slower processing speed: the Professional Fighters' Brain Health Study.

OBJECTIVES: Cumulative head trauma may alter brain structure and function. We explored the relationship between exposure variables, cognition and MRI brain structural measures in a cohort of professional combatants. METHODS: 224 fighters (131 mixed martial arts fighters and 93 boxers) participating in the Professional Fighters Brain Health Study, a longitudinal cohort study of licensed professional combatants, were recruited, as were 22 controls. Each participant underwent computerised cognitive testing and volumetric brain MRI. Fighting history including years of fighting and fights per year was obtained from self-report and published records. Statistical analyses of the baseline evaluations were applied cross-sectionally to determine the relationship between fight exposure variables and volumes of the hippocampus, amygdala, thalamus, caudate, putamen. Moreover, the relationship between exposure and brain volumes with cognitive function was assessed. RESULTS: Increasing exposure to repetitive head trauma measured by number of professional fights, years of fighting, or a Fight Exposure Score (FES) was associated with lower brain volumes, particularly the thalamus and caudate. In addition, speed of processing decreased with decreased thalamic volumes and with increasing fight exposure. Higher scores on a FES used to reflect exposure to repetitive head trauma were associated with greater likelihood of having cognitive impairment. CONCLUSIONS: Greater exposure to repetitive head trauma is associated with lower brain volumes and lower processing speed in active professional fighters.

The protective effect of education on cognition in professional fighters.

Education has a protective effect against cognitive deficits following various forms of brain insult. Professional fighting (boxing and mixed martial arts) provides a model for assessing the impact of cumulative brain injuries on cognition and brain health. In the current cross-sectional observational study, we explore whether education would be protective against cognitive loss in fighters. We tested 141 professional fighters using a computerized neurocognitive battery, in addition to structural MRI. We used automated segmentation software to compute the volumes of various brain structures. We found fighters with high school education or less to show more associations between fight exposure and cognitive test scores. The relationship between brain structure volume and exposure did not differ based on education. These results are interpreted as putatively showing a protective effect of education on functional integrity in fighters, although longitudinal data and a larger sample size are required to further understand this relationship.

Changes in cognition and health-related quality of life with unilateral thalamotomy for Parkinsonian tremor.

Cognitive functioning and health-related quality of life were assessed pre- and post-operatively in a consecutive series of 31 Parkinson's disease patients who underwent stereotactic unilateral thalamotomy (22 left-sided, 9 right-sided) for tremor alleviation. Neuropsychological functions assessed included verbal and visual memory, language and speech production, verbal and non-verbal reasoning, and attention and working memory. Health-related quality of life measures included both general and disease-specific questionnaires. We found a statistically significant post-operative decline in phonetic verbal fluency scores for left-operated patients, as well as improvements in self-ratings of stigma and bodily discomfort on the disease-specific quality of life questionnaire. These findings suggest that thalamotomy, when indicated, has limited cognitive sequelae and may result in improved quality of life in areas specific to Parkinson's disease.