Cumulative hits to the head during one season of football or hockey could leave a lasting impact on the brain and cognitive abilities, a new study suggests.
Collegiate contact sport athletes were more likely to score lower on
learning and memory tests at the end of the season compared to their test scores at season's start, compared to those who participated in
non-contact sports. In addition, those who had score declines had more changes in their white matter, a part of the central nervous
system responsible for conducting the speed of the nerve signals sent around
"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,” study author Dr. Thomas W. McAllister, the Albert Eugene Sterne Professor of Clinical Psychiatry at the Indiana University School of Medicine in Indianapolis, said in a press release.
The researchers tested 80 Division I NCAA Dartmouth College varsity football and ice hockey players who did not have a history of concussions, as well as 79 non-contact sport athletes who competed in non-contact sports like track, crew and Nordic skiing.
The athletes were all asked to take the California Verbal Learning Test II, which looked at verbal learning and memory, at both the beginning and end of the season. They also underwent an MRI brain scan that specifically looked at white matter.
Out of the athletes had a 1.5 standard deviation decline in test scores at the end of the season, 20 percent were in contact sports. Only 11 percent participated in non-contact activities. McAllister explained that a score drop of this magnitude in this time-frame was only expected in about 7 percent of the population.
The athletes who had scores drop greatly, regardless of sport, had many notable changes in their white matter compared to those whose scores did not go down. In particular, differences were seen in the corpus callosum, which is an area of nerves that connect the left and right sides of the brain.
"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.
The study was published in Neurology on Dec. 11.
According to the Centers for Disease Control and Prevention, U.S. emergency departments see about 173,285 sports- and recreation-related traumatic brain injuries a year just among patients under 19 years old. The rate has gone up 60 percent in the last decade.
Researchers are particularly concerned about head injures, due to the mounting evidence that shows that athletes who have experienced repeated blows to the head may develop a condition known as chronic traumatic encephalopathy (CTE). CTE is a Alzheimer's-like neurodegenerative brain disease that causes memory loss, confusion, impaired judgment, impulse control problems, aggression, depression and progressive dementia at younger ages than typical.
The condition can only be diagnosed in deceased patients, but recent progress has been made in diagnosing it in living people.
Brett Favre, who notoriously
played with a leave-it-all-on-the-field mentality, admitted he was suffering from memory problems and could not recall his daughter playing soccer.
Younger athletes may be at a higher risk of sustaining these brain injuries. An October report revealed that college athletes experience an estimated 6.3 concussions per 1,000 athletic exposures, which includes all practices and games. High school athletes sustained 11.2 concussions per 1,000 athletic exposures.
Previous studies have shown that patients who had mild concussions had notable differences in how the fluid traveled through their brain, even if they no longer had concussion symptoms. Concussions were also associated with white matter changes in kids’ brains.