Cognitive and emotional effects of one season of head impact exposure in high school contact sport athletes
Nowinski, Christopher John
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Short-term and long-term neurological damage as a result of sports-related brain trauma is a major concern for athletes today. In the last decade, studies of subconcussive repetitive head impacts (RHI) in contact sports have found associations with functional and structural brain changes, even in the absence of diagnosed concussion. Risk and thresholds for brain dysfunction in the setting of sports-related RHI remain poorly understood. This prospective study enrolled 119 athletes (72 contact, 47 noncontact) of both sexes (79 male, 40 female), to explore the effect of one season of subconcussive RHI on brain function in high school football, boys lacrosse, and boys and girls soccer versus a comparison group of noncontact athletes. This study is the first to assess the effects of one season of RHI exposure on traditional and novel cognitive measures as well as self-reported emotion, sleep and headache in high school athletes. Contact sport athletes wore a commercial accelerometer to investigate if there is a dose-response relationship between RHI exposure and brain function. Paired t-test comparisons of all measures revealed contact sport athletes were not different than noncontact athletes in experiencing negative changes over the course of one season on the assessment battery. Given the number of subjects evaluated and the resultant power to detect change, this study had an 82.5% power to detect a Cohenʼs d of 0.66. Regression analysis of multiple measures of RHI among contact sport athletes did not identify a significant relationship between exposure and changes in cognition, emotion, sleep or headache over one season. Secondary analyses found significant relationships between a greater number of total head impacts at postseason assessment and higher scores on NIH Emotion Battery elements Perceived Stress (p=0.0002) and Perceived Hostility (p=0.0004), but it was unrelated to total years of football exposure. Overall, this study showed that there does not appear to be an association between one season of RHI exposure and short-term changes in cognition or self-reported aspects of emotion, sleep, or headache. Results from this study may help in the design of future investigations that will increase our understanding of the short-term consequences of RHI. Future studies should concentrate on the question of a clinically significant threshold at which RHI above a certain magnitude is more likely to cause brain dysfunction.