Abstract:
Objective: Repeated mild traumatic brain injuries are believed to have detrimental long-term effects on the brain and cognition. Boxers frequently receive multiple sub-concussive and concussive blows during a fight, and are at risk for white matter damage as is seen in Traumatic Axonal Injury (TAI) given the rotational forces involved in blows to the head. The current study aims to examine the structural and functional connectivity among professional boxers immediately after a fight in which they experienced a concussion. Participants and Methods: A sample of 12 professional boxers with an average of 24 boxing-related concussions was compared to healthy controls. Within 48 hours of experiencing a concussion during a boxing match, boxers were scanned using structural and functional imaging modalities (i.e., T1, diffusion tensor imaging, and resting state functional MRI) and completed a computerized neuropsychological battery (ImPACT). White matter (WM) volumes, fractional anisotropy (FA), and hippocampal interhemispheric connectivity (i.e., BOLD synchrony) were measured using published techniques. Results: Compared to controls, boxers had significantly less WM, and lower FA within existing WM. Boxers displayed significantly less interhemispheric functional connectivity (IFC) between bilateral hippocampi. Number of concussions correlated strongly with reduced hippocampal IHC, slower processing speed, and impaired cognitive efficiency. All statistical analyses are significant at p < 0.05. Conclusions: Boxers demonstrate WM damage suggestive of axonal injury and possible Wallerian degeneration. Interhemisphereic functional connectivity for the hippocampus is compromised, and may be explained, at least in part due to the compromise of WM connections including the corpus callosum. While the results are preliminary, they suggest compromise to structural and functional connectivity among boxers may be associated with decreased neurocognition.