Cognitive effect of one season of head
impacts in a cohort of collegiate contact sport athletes.

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.

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

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
Reviewed by: Jeffrey


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