By Genevra Pittman
NEW YORK (Reuters Health) - Some students who play hockey and football may perform worse than expected on learning tests after a season of head impacts even if they never suffer an actual concussion, a new study suggests.
Researchers found that before their playing seasons started, college hockey and football athletes were just as sharp mentally as their peers in non-contact sports. But about one in five of the contact-sport athletes appeared to suffer some effects from a season's worth of head impacts.
"It provides a little bit of reassurance relative to the huge concerns that have been raised," said the study's lead author, Dr. Thomas McAllister, from the Geisel School of Medicine at Dartmouth in Lebanon, New Hampshire. The study was published on Wednesday in the journal Neurology http://bit.ly/lUcacJ.
At the same time, the study raises the question "is there a subgroup of people for whom hitting their head over and over again may not be a good thing?" McAllister said.
The findings come amid increasing scrutiny of brain injuries sustained by National Football League players. Two weeks ago, former San Diego Chargers star Junior Seau committed suicide after what some believe were years of depression stemming from multiple concussions he suffered as a player. That same week, 100 retired NFL players sued the league over head injuries.
Still, many questions remain about the effect of concussions on thinking and memory -- including whether or not repeated, less-severe blows to the head may also cause short-term or permanent damage.
469 HEAD BLOWS PER ATHLETE
For their study, McAllister and his colleagues recruited Division I varsity athletes at Dartmouth College, Brown University and Virginia Tech.
At the start and end of their athletic seasons, the researchers gave thinking and learning tests to 214 hockey and football players, as well as 45 athletes on non-contact sports teams -- such as track, crew and skiing -- for comparison.
The hockey and football players were outfitted with special helmets that recorded data on each of their head impacts, such as the head's acceleration after contact.
Over the course of the season, the helmets recorded an average of 469 head blows per athlete, a number that varied between one and over 2,000 impacts. No athletes who suffered a concussion during the course of the season were included in the analysis.
In general, there was no difference in how well contact and non-contact athletes performed on the series of thinking and memory tests -- either before their seasons started or after they ended.
But on one learning test, taken by a smaller group of 100 athletes, 22 percent of hockey and football players had worse-than-expected postseason scores, based on their own preseason performance. That compared to four percent of runners, rowers and skiers.
"What we don't know is how long these poorer-than-predicted people stayed in that category," McAllister told Reuters Health. "It may be that if we tested them six months later, it was fine."
A STARTING POINT
McAllister also pointed out that there was not a clear link between the number of times athletes got hit in the head, or how hard, and how they did on the postseason tests. So it may be that genetic differences between players affect how their mind and body respond to those repeated blows.
One concussion researcher not involved in the new study agreed the findings are reassuring, but cautioned against athletes, parents and coaches becoming complacent as a result.
"What we don't want is for athletes to say, ‘Unless I have a concussion, I don't have to worry about cognitive impairment,'" said Paul Comper, from the University of Toronto.
He added that the tools used to measure head impacts are still being developed -- and it is possible the helmets in the study were not recording all of the relevant measurements that could link hits to thinking and memory.
Some of the researchers reported a financial interest in the helmet technology.
(Editing by Ivan Oransky and Michele Gershberg)