Abstract
There is growing concern about how participation in contact sports affects the brain. Retrospective evidence suggests that contact sports are associated with long-term negative health outcomes. However, much of the research to date has focused on former athletes with significant health problems. Less is known about the health of current athletes in contact and collision sports who have not reported significant medical issues. In this cross-sectional study, advanced magnetic resonance imaging (MRI) was used to evaluate multiple aspects of brain physiology in three groups of athletes participating in non-contact sports (N = 20), contact sports (N = 22), and collision sports (N = 23). Diffusion tensor imaging was used to assess white matter microstructure based on measures of fractional anisotropy (FA) and mean diffusivity (MD); resting-state functional MRI was used to evaluate global functional connectivity; single-voxel spectroscopy was used to compare ratios of neural metabolites, including N-acetyl aspartate (NAA), creatine (Cr), choline, and myo-inositol. Multivariate analysis revealed structural, functional, and metabolic measures that reliably differentiated between sport groups. The collision group had significantly elevated FA and reduced MD in white matter, compared to both contact and non-contact groups. In contrast, the collision group showed significant reductions in functional connectivity and the NAA/Cr metabolite ratio, relative to only the non-contact group, while the contact group overlapped with both non-contact and collision groups. For brain regions associated with contact sport participation, athletes with a history of concussion also showed greater alterations in FA and functional connectivity, indicating a potential cumulative effect of both contact exposure and concussion history on brain physiology. These findings indicate persistent differences in brain physiology for athletes participating in contact and collision sports, which should be considered in future studies of concussion and subconcussive impacts.
Highlights
While the majority of athletes who participate in collision and contact sports do not present with debilitating clinical outcomes, there is a growing concern for the long-term brain health of these athletes
Somatic complaints showed a significant difference between groups, with higher scores for collision sports compared to non-contact sports, the effect was non-significant after adjusting for multiple comparisons at an false-discovery rate (FDR) of 0.05
This article presents a detailed comparison of white matter microstructure, resting brain function and cerebral metabolites, for athletes in sports associated with different levels of contact exposure
Summary
While the majority of athletes who participate in collision and contact sports do not present with debilitating clinical outcomes, there is a growing concern for the long-term brain health of these athletes. These concerns largely stem from studies that have identified elevated risk of depression, memory problems, cognitive impairments, and earlier onset of Alzheimer’s disease among former professional football players [1,2,3]. There has been limited research examining the brain health of athletes who are actively participating in contact sports These athletes may be exposed to hundreds of impacts over a single season [6, 7] and may be at risk of cumulative effects caused by repeated subconcussive blows [8]. Evaluating the brain physiology of current contact and non-contact athletes may help improve our understanding of the etiology underlying potential long-term health consequences of contact exposure
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