Cognitive Function as Related to Cumulative Head Impact Exposure in Football: Effects of Position

Abstract

Repetitive sub‐clinical head impacts are linked to progressive cognitive decline and chronic traumatic encephalopathy (CTE) diagnoses in professional contact‐sport athletes post mortem. There exists a gap however in understanding when this long‐term damage occurs, and specifically in determining the career stage when signs of injury can be first detected or even the influence of a single season of play. In 2014, our group used a 12‐test online cognitive battery (www.cambridgebrainsciences.com) to study the cognitive function of a population of 35 male varsity football athletes in both the pre‐ and post‐season. In comparison to controls, the athletes showed decreased scores in the pre‐season with no pre‐ to post‐season differences. Additionally, athletes’ concussion histories were not correlated with any cognitive measure.Given the positional variation in head impact exposure profiles and CTE diagnoses in football, the objective of the current study is to determine the influence of player position, and thus head impact exposure profile, on cognitive function over the course of a single season as well as the athletes’ careers up until this point. Participants consisted of an overlapping sample of athletes from the same football team for the 2014 and 2015 athletic seasons. Cognitive function was determined using cognitive battery scores and reaction times of players in both the pre‐ and post‐ season. Preliminary results, both aggregated and stratified by position demonstrate there was no difference between pre‐ and post‐season battery scores or reaction times. In accordance with our previous results, this suggests that a single season of head impact exposure does not cause significant cognitive decline. However, when considering all data as a representation of career‐long exposure, results suggest that wide receivers have the fastest reaction times on cognitive tests and consistently outperform their defensive linemen counterparts in terms of battery score. Defensive linemen also demonstrate the most variable reaction times. Previous studies analysing impact magnitude and frequency suggest that defensive linemen sustain significantly more low force hits while the wide receivers endure fewer hits but of high collision forces. Additionally, studies assessing the frequency of CTE diagnosis by position suggest fewer diagnoses in former wide receivers than in defensive linemen. Collectively, these results align well with previously published biomechanical and clinical literature and suggest that there is a continuum of cognitive function impairments across positions and head impact exposure profiles. Better characterization of the relationship between sport‐and position‐specific head impact exposure profiles and cognitive function may help guide participation, coaching strategies, and safe play decisions in sport.Support or Funding InformationResearch supported by CERC funding awarded to AMO