Grade-school football players may not ever experience a concussion, but just one season of "sub-concussive head impacts"—blows to the head that aren't quite severe enough to cause a full-blown concussion—could be enough to alter young athletes' brains, ABC News reports. Per a study in the journal Radiology, researchers from the Wake Forest School of Medicine, among others, examined the brains of 25 boys ages 8 to 13 playing in a North Carolina youth football league, both at the beginning of the season and again at the end, NBC News notes. And even though no subject logged an actual concussion, researchers found the more force a player was exposed to during the season, the more likely it was for him to have a lower fractional anisotropy (FA) score, an indicator of smoothly flowing water molecules in the brain that usually signifies healthy white matter.
The players donned a sensor-equipped helmet that registered the type of force each boy endured; these hard hits were backed up by tape viewings of games and practices. "They [were] hitting at extremely high levels," says a pediatric neurosurgeon involved with the study, per NBC. Scientists then compared an end-of-season MRI that measured the water movement for each player along nerve fibers with one taken at the beginning of the season—and found players who'd endured more force had lower FA scores, which have been tied in other studies to brain disruptions. Study co-author Christopher Whitlow, head of neuroradiology at the Wake Forest School of Medicine, concedes the sample size was small and that more research is needed, telling ABC, "There is more we don't know about these changes than we do know." (Brain injuries are popping up in the pro wrestling world, too.)