NEW YORK (Reuters Life!) - High school athletes are four times more likely to suffer a concussion today than they were about a decade ago, with football players leading the pack, according to a study.
What was more, concussions appeared to be an issue not only in sports long thought of as high impact, but also those thought of as low impact, with some high school athletes suffering from two or more concussions.
In 25 public schools from 1997 to 2008, and six different sports each for girls and boys, there were about five concussions for every 10,000 times high school athletes were on the field, the research -- published in the American Journal of Sports Medicine -- found.
That's up from slightly over one per 10,000 times on the field in 1997.
"Certainly the recognition of signs and symptoms of concussion have increased dramatically among the players, coaches, athletic trainers and physicians," study author Andrew Lincoln, who heads the Sports Medicine Research Center at Union Memorial Hospital in Baltimore, Maryland.
"Also, there's the issue of players performing better, getting stronger and getting faster," he told Reuters Health.
During the entire period, the chance that boys playing any sport would get a concussion was three in 10,000 exposures, compared to one in 10,000 exposures for girls.
Football was the riskiest sport, with a rate of about six concussions per 10,000. Boys' lacrosse and soccer came next. For girls, concussions were most common during soccer at three and a half per 10,000, followed by lacrosse and basketball.
However, when boys and girls played similar sports, girls were about twice as likely to get a concussion. The same has been found in college athletes, but nobody really knows why.
"We know that in general, females are more likely to seek medical care than males are," Lincoln said, adding there is also speculation that girls' bodies may be less able to absorb a hit.
More than 7.5 million U.S. high school students took part in school sports in the 2009-2010 school year, according to the National Federation of State High School Associations.
Of the 2,650 concussions recorded in the study, most were one-time occurrences. However, about 290 students suffered two concussions, and 26 had three or more.
Multiple concussions in high school students is of great concern, said Douglas Weibe, who studies concussions at the University of Pennsylvania and who was not part of the study.
"The risk there is second impact syndrome, which essentially means that the brain is still recovering from trauma from the first concussions, and it sustains a second impact," he told Reuters Health.
Sports concussions cause an average of 1.5 deaths per year, and most of these are due to a second concussion, according to the American Association of Neurological Surgeons.
In August, the American Academy of Pediatrics' Council on Sports Medicine and Fitness suggested that children with concussions be cleared by a doctor before heading back onto the field.
But concussions can be hard to diagnose sometimes and formal guidelines to define them haven't been established, Weibe said.
"Right now doctors don't know how best to manage concussion and how to make decisions on when it's safe for a kid to return to play," he said.
"That's an area of research that's greatly needed."
Reporting by Leigh Krietsch Boerner at Reuters Health; editing by Elaine Lies