A single high-school football season of heavy hits, even without a concussion, led to observable brain abnormalities in a new study, the latest evidence to raise questions about the long-term consequences of the popular game.
The findings from 24 high-school athletes suggest that a series of small, successive blows to the head can prompt changes in the brains of young people. The research was presented today at the annual meeting of the Radiological Society of North America.
The study didn’t look at brain function, so the cognitive effect of the observed brain-structure changes remains unknown. A 2013 analysis of 80 Division I college football and ice-hockey players, though, found that the more the brain changed over a single season, the worse athletes did on learning and memory tests.
“There’s a lot we don’t know about these changes. Do they persist over time? Do they go away? Are they associated with some subtle cognitive changes?” said Christopher Whitlow, an associate professor of radiology at Wake Forest School of Medicine in North Carolina. “We haven’t really answered those questions yet, but are planning to in the future.”
Most attention to brain injury during football has been focused on professional players. Yet there are only 1,700 National Football League players, compared with 2.8 million young people who play the sport in the U.S.
“We know little about head injury risks for those youth football players,” said Whitlow. “If we can identify risks, then we can intervene, decrease the risks, and make this sport as safe as possible for all the children who are playing it.”
Heavy Hitters
The study is the latest in a series of analyses from the Wake Forest’s Kinematics of Impact Data Set, or KIDS, project, the largest study of its kind to assess head impacts in youth football.
During games and practice for a single football season, the researchers outfitted the players, ages 16 to 18, with accelerometers on their helmets to detect how many head impacts the players had and how hard the hits were.
Before the season, the players underwent advanced MRI scans, called diffusion tensor imaging, or DTI, which detects the microstructure of the brain’s white matter -- the millions of nerve fibers called axons that transmit information around the brain.
Based on the accelerometer data, the researchers categorized the players in two groups -- identifying nine heavy hitters and 15 light hitters.
Corpus Callosum
After the season, they were scanned again. The tests found that the heavy hitters showed statistically significant abnormalities in the white matter in specific parts of the brain -- notably the corpus callosum and deep white matter tracts -- areas previously found to be altered after mild traumatic brain injuries.
The brain changes occurred despite the fact that none of the players were found to have experienced a concussion during the season.
More research needs to be done. “It is unclear whether or not these effects will be associated with any negative long-term consequences,” Whitlow said in a statement accompanying the study.
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