Diffusion Measures Indicate Fight Exposure-Related Damage to Cerebral White Matter in Boxers and Mixed Martial Arts Fighters

Imaging Institute and Neurological Institute, Cleveland Clinic, Cleveland, Ohio
American Journal of Neuroradiology (Impact Factor: 3.59). 08/2013; 35(2). DOI: 10.3174/ajnr.A3676
Source: PubMed


Background and purpose:
Traumatic brain injury is common in fighting athletes such as boxers, given the frequency of blows to the head. Because DTI is sensitive to microstructural changes in white matter, this technique is often used to investigate white matter integrity in patients with traumatic brain injury. We hypothesized that previous fight exposure would predict DTI abnormalities in fighting athletes after controlling for individual variation.

Materials and methods:
A total of 74 boxers and 81 mixed martial arts fighters were included in the analysis and scanned by use of DTI. Individual information and data on fight exposures, including number of fights and knockouts, were collected. A multiple hierarchical linear regression model was used in region-of-interest analysis to test the hypothesis that fight-related exposure could predict DTI values separately in boxers and mixed martial arts fighters. Age, weight, and years of education were controlled to ensure that these factors would not account for the hypothesized effects.

We found that the number of knockouts among boxers predicted increased longitudinal diffusivity and transversal diffusivity in white matter and subcortical gray matter regions, including corpus callosum, isthmus cingulate, pericalcarine, precuneus, and amygdala, leading to increased mean diffusivity and decreased fractional anisotropy in the corresponding regions. The mixed martial arts fighters had increased transversal diffusivity in the posterior cingulate. The number of fights did not predict any DTI measures in either group.

These findings suggest that the history of fight exposure in a fighter population can be used to predict microstructural brain damage.

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Available from: Wanyong Shin, Nov 25, 2014
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    • "Like previous investigators, we found a significant relationship between number of fights and mean diffusivity values in the posterior corpus callosum. In addition, the number of times a fighter has been knocked out in his career predicted increased longitudinal and transverse diffusivity in white matter and subcortical gray matter regions including corpus callosum, cingulate, pericalcarine, precuneus, and amygdala, leading to increased mean diffusivity and decreased fractional anisotropy values in the corresponding regions in ROI analysis [35]. Preliminary analysis of resting-state functional MRI from a left posterior cingulate cortex seed showed that greater number of fights and KOs was associated with more impairment in the functional connectivity in anterior cingulate and cingulate gyrus (Figure 2). "
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