mTBI: Project Description

Sports-related concussion (SRC) receives significant public attention due to its link with professional athletics, but the annual incidence of SRC in high school and collegiate populations greatly exceeds that of professional athletes. SRC was historically viewed as a benign injury, but there is growing concern over the cumulative effects of both SRC and sub-concussive head injury. A major limit to research of SRC is the lack of objective physiologic markers to evaluate the degree of injury. Current assessment of injured athletes for return-to-play relies primarily on self-reported symptoms and behavioral metrics. These assessment tools demonstrate significant test-retest variability and are potentially manipulated by athletes motivated to return to play. It also remains unknown whether normalization of the assessment metrics reflects an athlete truly returning to baseline regarding the underlying brain pathophysiology. Our study will use advanced magnetic resonance imaging (MRI) techniques to study brain physiology of adolescent male athletes in two school sports at risk for SRC – football and lacrosse. Unlike other imaging studies of head impact, our design will compare post-impact athletes against their own pre-season baselines. In addition, athletes will be stratified based on the number and severity of head impacts, as measured by wireless impact-sensing mouth-guards. Quantifying head impact will allow us to evaluate both the acute effects of sub-concussive head impact and the chronic effects of cumulative head impact, a significant advance from simply looking at concussed athletes. Our MRI metrics will include: 1) high-resolution anatomy, assessing cortical thickness, 2) resting state functional MRI, measuring grey matter connectivity, 3) diffusion tensor imaging, measuring white matter integrity, 4) proton magnetic resonance spectroscopy, measuring brain chemical composition, and 5) susceptibility weighted imaging, looking for micro-hemorrhages in the brain tissue. This battery of MRI metrics is selected for its likelihood to describe the physiologic signature of mild traumatic brain injury; and it represents a test that could be easily deployed on the thousands of clinical MRI scanners already available to the US population.