Longitudinal Changes in Cognitive Functioning and Brain Structure in Professional Boxers and Mixed Martial Artists After They Stop Fighting

dc.creatorZhuang, Xiaowei
dc.creatorBennett, Lauren
dc.creatorNandy, Rajesh
dc.creatorCordes, Dietmar
dc.creatorBernick, Charles
dc.creatorRitter, Aaron
dc.description.abstractOBJECTIVE: This study compares longitudinal changes in cognitive functioning and brain structures in male fighters who transitioned to an inactive fighting status without any further exposure to repetitive head impacts (RHI) and fighters remaining active with continual exposure to RHI. METHODS: Participants were recruited from the Professional Fighters Brain Health Study. At time point 1 (TP1), all fighters were active, with continual exposure to RHI. At time point 2 (TP2), fighters were considered transitioned" if they had no sanctioned professional fights and had not been sparring for the past 2 years. Fighters were considered "active" if they continued to train and compete. All fighters underwent cognitive testing and 3T magnetic resonance imaging (MRI) at both TPs. A subset of our fighters (50%) underwent blood sampling for characterization of neurofilament light (NfL) levels at both TPs. Linear mixed effect models were applied to investigate the potentially different longitudinal trajectories (interaction effect between group and time) of cognitive function measures, NfL levels and regional thickness measures (derived from structural MRI) between transitioned and active fighters. RESULTS: 45 male transitioned fighters (31.69+/-6.27 years old (TP1), 22 boxers, 22 mixed martial artists, 1 martial artist) and 45 demographically matched male active fighters (30.24+/-5.44 years old (TP1); 17 boxers, 27 mixed martial artists, 1 martial artist) were included in the analyses. Significantly different longitudinal trajectories between transitioned and active fighters were observed in verbal memory (p (FDR) =4.73E-04), psychomotor speed (p (FDR) =4.73E-04), processing speed (p (FDR) =3.90E-02) and NfL levels (p=0.02). Transitioned fighters demonstrated longitudinally improved cognitive functioning and decreased NfL levels, and active fighters demonstrated declines in cognitive performance and stable NfL levels. Out of 68 cortical regions inspected, 54 regions demonstrated a consistently changing trajectory, with thickness measures stabilizing on a group level for transitioned fighters and subtly declining over time for active fighters. CONCLUSION: After fighters' cessation of RHI exposure, cognitive function and brain thickness measures may stabilize and blood NfL levels may decline. This study could be a starting point to identify potential predictors of individuals who are at a higher risk of RHI-related long-term neurological conditions."
dc.description.sponsorshipThis study is supported by the NIH (NIA-grant 1RF1AG071566, NIGMS-grant P20GM109025, and NIA-grant P20AG068053). This study, as part of the PFBHS, is supported by Lincy Foundation, Belator, Ultimate Fighting Championship Company (UFC), the August Rapone Family Foundation, Top Rank, and Haymon Boxing.
dc.identifier.citationZhuang, X., Bennett, L., Nandy, R., Cordes, D., Bernick, C., & Ritter, A. (2022). Longitudinal Changes in Cognitive Functioning and Brain Structure in Professional Boxers and Mixed Martial Artists After They Stop Fighting. Neurology, 99(20), e2275-e2284. Advance online publication. https://doi.org/10.1212/WNL.0000000000201158
dc.publisherWolters Kluwer Health, Inc.
dc.rights.holder© 2022 The Author(s).
dc.rights.licenseAttribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
dc.subjectactive professional fighters
dc.subjectcognitive functioning
dc.subjectfighters transition to an inactive status
dc.subjectrepetitive head impacts (RHI)
dc.titleLongitudinal Changes in Cognitive Functioning and Brain Structure in Professional Boxers and Mixed Martial Artists After They Stop Fighting


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