Cognitive effect of one season of head impacts in a cohort of collegiate contact sport athletes.
McAllister TW, Flashmasn LA, Maerlender A, Greenwald RM, Beckwith JG, Tosteson TD, Crisco JJ, Brolinson PG, Duma SM, Duhaime AC, Grove MR and Turco JH. Neurology. 2012. 78:1777-1784.
Recently in many media outlets, concerns have been raised over the long-term effects of head impacts on athlete’s cognitive function. While many studies have looked at the effects of mild traumatic brain injuries, few studies have looked at repetitive head impacts and their long-term effects. Therefore, McAllister and colleagues completed a pretest/posttest cohort study to evaluate if repetitive head impacts sustained over 1 season would affect cognitive performance. Two cohorts (214 contact sport [football and ice hockey] athletes and 45 noncontact sport [track, crew and Nordic skiing] athletes) from 3 participating division 1 universities were used in this study. All patients underwent testing that included the Immediate Post-Concussion Assessment and Cognitive test (ImPACT) at both preseason and postseason. Participants from 1 of the 3 universities (45 contact and 55 noncontact athletes) also underwent additional neuropsychological testing to assess general level of intellectual functioning, attention/concentration, working memory, verbal and visual learning and memory, verbal fluency, and processing speed. To measure head impacts all participants in the contact sport group were asked to wear the Head Impact Telemetry (HIT) system (composed of 6 single-axis accelerometers) in their helmets during all practices and games. The results of this study suggested that the ImPACT scores were no major differences between cohort’s scores before or after the season. Of the participants who underwent additional neuropsychological testing, non-contact athletes performed better on the Paced Auditory Serial Addition Task (assessing capacity and rate of information processing) than the contact participants during preseason, but, at the postseason follow-up, this was reversed with noncontact participants scoring more poorly than the contact sport athletes. Differences on the California Verbal Learning Test (assessing verbal learning and memory) were also observed with noncontact athletes improving more after the season than the contact participants. Analysis of the biomechanical data from the HIT system and ImPACT scores suggested a trend of poorer testing scores when the patient was exposed to more head impacts, but this did not reach statistical significance.
Overall this study supports the notion that repetitive head impacts over 1 season of competition may have detrimental effects on an athlete’s cognitive ability (based on the California Verbal Learning Test results). Interestingly, only the noncontact participants of the study were asked about a prior history of concussions despite contact athletes undoubtedly having a greater likelihood of experiencing a concussion. This begs the question: are the baseline scores truly baseline or is the athlete’s scores deviated from the scores they would have received before being subjected to any repetitive head impacts concussions? Without knowing more details about the past medical history, these finding may be statistically significant but their clinical significance cannot be truly understood. Studies similar to this, but with follow-ups over multiple seasons would be interesting and may shed some light on this matter. Despite this limitation, this study should make clinicians aware of the potential consequences that just one season of contact may have an impact on an athlete’s cognitive ability. Clinicians should be diligent in baseline testing so that they can adequately detect these subtle changes. What have you seen in you athletes? Do you think athletes experience an overall decline in their cognitive ability from the beginning to the end of the season?
Written by: Kyle Harris
Reviewed by: Jeffrey Driban
Related Posts:McAllister, T., Flashman, L., Maerlender, A., Greenwald, R., Beckwith, J., Tosteson, T., Crisco, J., Brolinson, P., Duma, S., Duhaime, A., Grove, M., & Turco, J. (2012). Cognitive effects of one season of head impacts in a cohort of collegiate contact sport athletes Neurology, 78 (22), 1777-1784 DOI: 10.1212/WNL.0b013e3182582fe7