Blows to the head during one season of ice hockey or football may affect the brains' white matter and cognitive abilities even if the athletes do not have a concussion, suggests a new study by the American Academy of Neurology. The study was published in the December 11, 2013, online issue of "Neurology."
“We found differences in the white matter of the brain in these college contact sport athletes compared to non-contact sport varsity athletes,” said study author Thomas W. McAllister, MD, of the Indiana University School of Medicine in Indianapolis. “The degree of white matter change in the contact sport athletes was greater in those who performed more poorly than expected on tests of memory and learning, suggesting a possible link in some athletes between how hard/often they are hit, white matter changes, and cognition, or memory and thinking abilities.”
Researchers recorded the acceleration time of head injuries of 80 concussion-free ice hockey and varsity football players from Division I NCAA Dartmouth College. The athletes wore helmets during play. The results were compared to those of 79 non-contact sport athletes who did crew, track, and Nordic skiing. The athletes were assessed with brain scans, and took memory and learning tests before and shortly after the season.
Researchers found that a subgroup of both types of athletes performed worse than they expected on memory and verbal learning tests at the end of the season. The score decline was more than 1.5 standard deviations below the predicted score. McAllister said that the large decline shown by 11 percent of the non-contact athletes and 20 percent of the contact players would be expected in less than 7 percent of a normal population.
“This group of athletes with different susceptibility to repetitive head impacts raises the question of what underlying factors might account for the changes in learning and memory, and whether those effects are long-term or short-lived,” said McAllister.