Functionally-Detected Cognitive Impairment in High School Football Players without Clinically-Diagnosed Concussion

TLDR

Repeated head collisions in football players can cause brain damage even without clinical concussion, a concern highlighted by media coverage and postmortem studies. The study aims to improve detection and characterization of head trauma to reduce injury risk and guide new therapies. Eleven high‑school athletes were monitored longitudinally with the HIT collision system, ImPACT neurocognitive testing, and fMRI to assess neurological changes. Three injury categories emerged: (1) no concussion and no change, (2) concussion with behavioral changes, and (3) asymptomatic players with measurable visual working‑memory deficits and altered dorsolateral prefrontal cortex activation linked to frequent top‑front collisions, indicating under‑detected neurological injury that may elevate future risk.

Abstract

Head trauma and concussion in football players have recently received considerable media attention. Postmortem evidence suggests that accrual of damage to the brain may occur with repeated blows to the head, even when the individual blows fail to produce clinical symptoms. There is an urgent need for improved detection and characterization of head trauma to reduce future injury risk and promote development of new therapies. In this study we examined neurological performance and health in the presence of head collision events in high school football players, using longitudinal measures of collision events (the HIT(™) System), neurocognitive testing (ImPACT(™)), and functional magnetic resonance imaging MRI (fMRI). Longitudinal assessment (including baseline) was conducted in 11 young men (ages 15-19 years) participating on the varsity and junior varsity football teams at a single high school. We expected and observed subjects in two previously described categories: (1) no clinically-diagnosed concussion and no changes in neurological behavior, and (2) clinically-diagnosed concussion with changes in neurological behavior. Additionally, we observed players in a previously undiscovered third category, who exhibited no clinically-observed symptoms associated with concussion, but who demonstrated measurable neurocognitive (primarily visual working memory) and neurophysiological (altered activation in the dorsolateral prefrontal cortex [DLPFC]) impairments. This new category was associated with significantly higher numbers of head collision events to the top-front of the head, directly above the DLPFC. The discovery of this new category suggests that more players are suffering neurological injury than are currently being detected using traditional concussion-assessment tools. These individuals are unlikely to undergo clinical evaluation, and thus may continue to participate in football-related activities, even when changes in brain physiology (and potential brain damage) are present, which will increase the risk of future neurological injury.