When a person has a concussion, headaches, memory impairment, and loss of balance usually make the injury obvious. But there are "many more people who are getting hit and getting hurt" without much attention, CTE researcher Lee Goldstein tells NPR. His latest study puts a spotlight on them, providing what Goldstein says is "solid scientific evidence" that hits to the head—even one—result in brain changes associated with CTE, independent of concussion. Goldstein, together with an international team of researchers, examined the brains of four football players, aged 17 or 18, who died a day to four months after a head injury. Compared to the brains of similarly-aged athletes who didn't experience head trauma, all four showed brain changes "including leaky blood vessels and abnormal buildups of the protein tau," which is associated with CTE, reports CNN.
The same changes were found in the brains of mice subjected to repeated and single-blast head trauma regardless of whether the mice experienced concussions, which could explain why 20% of athletes diagnosed with CTE had no record of concussion, Goldstein tells CBS News. Chris Nowinski of the Concussion Legacy Foundation translates the results to the NFL, noting the average hit, after which a player appears to recover, "probably wasn't fine, and that poor guy can't feel the damage that's happening in his brain." Indeed, "CTE develops early, soon after injury. It doesn't take years, or decades," Goldstein explains, adding the brain of one athlete studied already showed early-stage CTE. He says the research should be carefully considered by parents before kids are allowed to play football and other sports where hits to the head occur. (CTE has been found in a living patient, in a world first.)