Association Between Head Impacts, Reaction Time, And Cognitive Accuracy In Youth Football

Previous research has debated whether repetitive head impacts lead to negative clinical outcomes, such as impaired cognitive function. If so, those who participate in high-impact sports, such as football (flag or tackle), at a younger age may be at greater risk. Clinical reaction time (RT), a commonly measured cognitive outcome, can be subdivided into Simple and Complex RT. PURPOSE: To evaluate associations between RT and cognitive task accuracy relative to head impact magnitude and frequency in a cohort of youth football players (tackle [TF] and flag [FF]) throughout a season. METHODS: Twenty-nine youth football players (10.4 ± 0.5 years, TF = 17, FF = 12) wore head impact monitors (Triax) throughout all practices and games during one season. We collected average impact magnitude (linear acceleration [g], rotational acceleration [rad/s2]) and total number of impacts for each player. These variables, along with pre-season performance on each outcome, were independent variables. Dropstick RT (Simple RT [ms]), Stroop RT (Complex RT [ms]) and Stroop accuracy were dependent variables. We performed multiple linear regressions for RT measures (2 models) and repeated measures logistic regression for Stroop accuracy (1 model); Alpha = 0.05 for all analyses. RESULTS: Within the season, players sustained 94.2 ± 86.5 impacts with a magnitude of 42.3 ± 7.7 g and 5453.3 ± 1652.9 rad/s2. A higher number of impacts was associated with slower Complex RT (B = 0.737, p = 0.021) but quicker Simple RT (B = -0.187, p = 0.033). We observed no significant associations between RT and impact magnitude (p > 0.380) or between head impact frequency or magnitude and Stroop accuracy (p > 0.581). CONCLUSION: Youth football players that sustained more frequent head impacts presented with slower Complex RT after a single season. In contrast, football players that sustained more frequent head impacts presented with quicker Simple RT. Though statistically significant, the contrasting results and small effect sizes may limit the clinical meaningfulness of our findings. Head impact magnitude does not appear to be associated with RT or Stroop accuracy outcomes. Future repetitive head impact research should consider RT complexity when selecting a testing method and further explore whether this represents a meaningful clinical change. Supported by: Funding for this project was provided by the National Operating Committee on Standards for Athletic Equipment