The Effects of Subconcussive Head Impacts on Neurocognitive Performance in Collegiate Football Athletes

Chronic traumatic encephalopathy (CTE) is progressive degeneration of the brain that has been found in multiple case reports of American football athletes. A major predictor of CTE are subconcussive head impacts. Repetitive head impacts that do not result in signs or symptoms of a concussion have been termed ‘subconcussive head impacts.’ Researchers have begun to identify characteristics of subconcussive head impacts experienced during football (e.g., amount, force, speed, and direction of impacts), but to date, changes in these characteristics have not been described over the course of a full collegiate football season. In addition, research on the effects of subconcussive head impacts on neurocognitive performance is inconsistent. Neurocognitive performance is defined as the capability to think and reason through concentration, recall, learning, and processing information. Therefore, in this study we aimed to describe subconcussive head impacts experienced by American football athletes throughout a full collegiate season, and to evaluate the effect of a full season of subconcussive head impacts on neurocognitive performance through the assessment of complex brain activities, or cognition. National Collegiate Athletic Association (NCAA) Division I Football athletes from two programs served as participants (n=39, age 20.4+1.6 years). The data to describe subconcussive head impacts were collected through an accelerometer that attached to the participants’ helmets during all practices and games. The assessment of cognition was conducted through a testing battery, the Cambridge Neuropsychological Test Automated Battery (CANTAB). We found that over the course of one full season, participants experienced a mean of 824.5 head impacts at varying forces. Performance on assessments of memory, reaction time, and flexible thinking decreased from the start of the season to the end of the season. In addition, participants who experienced a higher amount of head impacts and who experienced a higher rotational speed of the head upon impact, performed worse on the assessments of neurocognitive performance. These results suggest an important target for decreasing the consequences of repetitive head impacts, such as a reduction in the amount of contact practices in exchange for film study or other non-contact options.