A single season playing football might be all it takes to change a young athlete's brain.
Those are the preliminary findings of research presented this week in Chicago at the annual meeting of the Radiological Society of North America.
Researchers used special MRI methods to look at nerve bundles in the brain in a study of the brains of 26 young male football players, average age 12, before and after one season. Twenty-six more young males who didn't play football also got MRI scans at the same time to be used as a control group.
In the youths who played football, the researchers found that nerve fibers in their corpus callosum — the band that connects the two halves of brain — changed over the season, says lead study author Jeongchul Kim, a research associate in the Radiology Informatics and Imaging Laboratory at Wake Forest School of Medicine in Winston-Salem, N.C.
"We applied here two different imaging approaches," he says. One analyzed the shape of the nerve fibers and the other focused on the integrity of the nerves.
Kim says the researchers found some nerve bundles grew longer and other bundles became shorter, or contracted, after the players' initial MRI scans at the beginning of the season. He says they saw no changes in the integrity of the bundles.
The team says these results suggest that repeated blows to the head could lead to changes in the shape of the corpus callosum, which is critical to integrating cognitive, motor and sensory functions between the two hemispheres of the brain, during a critical time for brain development in young people.
The researchers say their ultimate goal is to help inform guidelines for safer football play for youths.
Since the discovery of the degenerative brain disease chronic traumatic encephalopathy in the early 2000s, most of the research into the consequences of repeated head injuries during sports has been on adult athletes. This focus has occurred despite growing concerns that young athletes who experience the same kinds of collisions may also be vulnerable to their effects.
Radiologist Christopher Whitlow, a co-author of the new findings, says while the stories about NFL and collegiate players are very important, they have to be put into context.
"You have to understand that the NFL players were also most likely once collegiate players, they were also high school players and they were also probably youth players," he says. "To us, it's more than a question about concussions, it's a question about long-term cumulative exposure."
That being said, both Whitlow and Kim caution against making their findings out to be more than what they are: preliminary results from a single study with a relatively small number of participants.
"We don't know what it means," says Whitlow. "The natural next question is, do these changes persist over time? Do they accumulate with multiple seasons? And then No. 3, probably the most important: Do they have any relevance to long-term health?"
The results, presented at a medical meeting, haven't been published in a peer-reviewed journal. Whitlow says that the team is working on a paper to be submitted to a journal.
These latest findings are actually part of a years-long research collaboration among University of Texas Southwestern Medical Center, Wake Forest University and Children's National Health System in Washington, D.C.
Dr. Gerard Gioia is a pediatric neuropsychologist at Children's National Health whose role in the larger study is to look at the functional outcomes of kids playing football. He says these latest findings are only a part of the piece of the puzzle they're trying to solve.
"Everybody wants to know, 'Should my kid play football? Should my kid play soccer? Should my kid play ice hockey?' And we say, 'Can we please study this and understand it?' " says Gioia, who has been pushing for funding for more long-term studies into youth and sports.
For now, he says, they still have a lot of unanswered questions.