Head Impacts in Sports May Reduce Student-Athletes' Learning Ability
Certain contact sports, such as football and ice hockey, may hinder some student-athletes' ability to learn and remember new information, suggests a study published online Wednesday in the journal Neurology.
However, at a group level, repetitive head impacts over the course of a single season don't appear to have detrimental short-term effects on cognitive function for contact-sport athletes, the study found.
Researchers examined a mostly male group of 214 contact-sport athletes and 45 noncontact-sport athletes from three Division 1 schools who completed both preseason and postseason ImPACT tests. In addition, 55 noncontact-sport athletes and 45 contact-sport athletes completed a neuropsychological test battery along with the pre- and postseason ImPACT tests.
Of the 45 contact-sport athletes who completed the neuropsychological test, 22 percent finished more than 1.5 standard deviations below their expected score. Of the 55 noncontact-sport athletes who took the same test, only 4 percent finished more than 1.5 standard deviations lower. This discrepancy was deemed statistically significant by the researchers.
These findings suggest that "there may be a subgroup of athletes for whom repetitive head impacts affect learning and memory at least on a temporary basis," the study authors wrote.
"The good news is that overall there were few differences in the test results between the athletes in contact sports and the athletes in noncontact sports," said study author Dr. Thomas McAllister of the New Hampshire-based Geisel School of Medicine at Dartmouth, in a statement. "But we did find that a higher percentage of the contact-sport athletes had lower scores than would have been predicted after the season on a measure of new learning than the noncontact-sport athletes."
The contact-sport athletes were exposed to an average of 469 separate head impacts over the course of a season, according to the study. No athlete who endured a concussion during the season was included in the study.
On a potentially positive note, the researchers didn't find any association between accumulated head impacts over previous seasons and reduced cognitive performance when comparing contact- and noncontact-sport athletes.
"These results are somewhat reassuring, given the recent heightened concern about the potential negative effects of these sports," said McAllister. "Nevertheless, the findings do suggest that repetitive head impacts may have a negative effect on some athletes."
McAllister and his colleagues noted a few limitations to the study, including the sample size (limited to collegiate athletes, so "care must be taken in extrapolating the results to different age groups") and imperfections in the ImPACT tests and neuropsychological test battery.
The authors are quick to say that more research, including a longer (potentially four-year) sample is needed before drawing further conclusions.
In an editorial published in Neurology as a supplement to the study, Dr. Ellen Deibert and Richard Kryscio, associate editor of Neurology, warn that the answer to the question, "How many hits is too many?" is still unknown for athletes of all ages. They echo McAllister's call for further research into head injuries.
"The magnitude and frequency of hits will not be the only answer," they warn, as there are a number of other clinical variables to consider when evaluating head injuries in athletes.
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