A History of Fight Exposure Predicts DTI Measures in Fighter Populations

Wanyong Shin¹, Shamseldeen Mahmoud¹, Ken E. Sakaie¹, Banks Sarah², Mark J. Lowe¹, Michael Phillips¹, Michael T. Modic¹, Charles Bernicks²

Fighting athletes such as boxers are at risk for traumatic brain injury (TBI). Because diffusion tensor imaging (DTI) is sensitive to microstructure changes in white matter (WM), this technique is often used to investigate WM integrity in patients with TBI. We hypothesized that previous fight exposure would predict DTI values in a fighter population after controlling for individual confounding variables such as (age, weight, and years of education). We found that the number of times a fighter has been knocked out in his career predicted increased longitudinal diffusivity in corpus callosum and fornix regions and increased transverse diffusivity in corpus callosum, fornix, left hippocampus and left posterior corona radiate, leading to the increased mean diffusivity and decreased fractional anisotropy values in the corresponding regions. Our finding suggests that DTI values indicating micro-structural brain damage correlate with the history of fight exposure in a fighter population.