Blows to Head Even Without a Concussion Affects Learning, Memory

Blows to head even without a concussion may affect the white matter of the brain, resulting in reduced cognition or thinking abilities, according to a new study.

The study reported in the journal of American Academy of Neurology, claims that even in the absence of a concussion, a blow to the head during a single season of football or ice hockey may affect the white matter in the brain, which is known to play a key role in regulating speed of the nerve signals.

"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 Indiana University School of Medicine in Indianapolis, according to a news release. "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."

The study was conducted on 80 players who were concussion free and were a part of the Division I NCAA Dartmouth College varsity football and ice hockey. These players wore helmets that recorded the acceleration-time of the head immediately after a hit or an impact.

The study subjects were later compared to nearly 79 non-contact sport athletes who were involved in activities like crew, Nordic skiing and track. Before and after the seasons, the players were assessed with brain scans and learning and memory tests.

The researchers noticed that the subgroup of both the types of athletes performed worse when verbal learning and memory tests were conducted at the end of the season. Also just 20 percent of contact players and 11 percent of the non contact athletes achieved better score, they scored more than 1.5 standard deviations below the predicted score.

 Such a large scale drop can be expected in less than seven percent of a normal population. Major alterations were noticed in the corpus callosum area of the brain in the subgroup when compared to the athletes who achieved scores as predicted on tests.

"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.