Football Head Impacts Can Cause Brain Changes Even Without Concussion

As the world mourns the loss of Ohio State University football player Kosta Karageorge, who was found dead in an apparent suicide on Nov. 30, concerns about the long term effects of head injuries sustained by footballers continue to mount. A day after Karageorge’s death, a study has been released that suggests sports-related head impacts can cause changes in the brain even when there are no outward signs of a concussion.

In fact, researchers from Wake Forest Baptist Medical Center in Winston-Salem, N.C., say some high school football players in the study exhibited measurable brain changes after a single season of play, even in the absence of concussion.

The Wake Forest team, lead by Dr. Christopher Whitlow, focused on youth players, a group that until now had been widely overlooked in the research into the effects of the repetitive head impacts associated with a typical season of football. “For every one NFL player, there are 2,000 youth players. That’s close to four million youth players and the vast majority of research on impact-related brain injuries has been on the college and professional level,” says Dr. Whitlow, noting that two-thirds of head impacts occur in practice sessions, not games.

Read More: High School Football Player Dies After Injury

In the first-of-its-kind study, the researchers hooked up 24 high school football players between the ages of 16 and 18 with helmet-mounted sensors to assess the frequency and severity of helmet impacts and then sent them out to play ball. As the players hit the field, the sensors allowed the researchers to monitor the severity of players’ head impacts. The team collected data from the helmets before and after every game and the high school students also underwent pre- and post-season diffusion tensor imaging (DTI) of the brain. “We looked at both structural and functional neuro-imaging and evaluated the players’ neuro-cognitive function,” he says.

“We found some changes in the brain that are concerning,” said Dr. Whitlow. “They are concerning because kids with more impacts had more changes and the kids with fewer impacts had fewer changes.”

While none of the football players were concussed during the season, the researchers found that there were microstructural changes in all of the players’ brains, especially in those players who were deemed “heavy hitters.” That direct correlation between game-related hits and changes in the brain is not exactly surprising, but may be unsettling for parents of youth football players.

Read More: The Tragic Risks of American Football

Not that Dr. Whitlow wants people to pull their kids from the peewee leagues or ban high school football just yet. “The high school athletes weren’t experiencing any of the classic symptoms of concussion—dizziness, nausea or double vision,” he says. “While the changes in the brains are concerning, because there were no symptoms of concussions, we don’t yet know how important these changes are.”

Dr. Whitlow sees the results of the study as only the first step in identifying a potential problem with allowing youth players to continue to play ball. He and his team want to determine whether these changes in the brain are permanent or transient and whether they are associated with subtle changes in neuro-cognitive functions. “Once we can identify risks, we can intervene to reduce those risks,” he says. Interventions could include improvements in technology and helmet safety, identifying maneuvers that could be particularly dangerous, making changes in the diagnoses of head injuries and identifying subtle changes that could be harmful.

So what’s a parent to do? Dr. Whitlow suggests they get involved in their kids’ practices. “You have to put these risks in the context of the health-related benefits of playing sports. The take home message is that parents need to use common sense. The best thing for parents to do is know what is going on on the field, know the symptoms of concussions, get to know the coaches, find out if there is a trainer on the field who can diagnose concussions.” He also directed parents to SaveInjuredKids.org for ideas on how to reduce head injuries and to learn to identify the signs of concussion.

“Football is the great American pastime,” said Dr. Whitlow. “I think it’s going to be around for another hundred years and what we’re trying to do is make it safer.”

Got Kids? Special Offer for Families from TIME