This was well understood in the field, but difficult to prove. Kudos...
A study published online Thursday in Brain, a journal of neurology, presents the strongest case yet that repetitive hits to the head that don't lead to concussions —meaning no loss of consciousness or other symptoms that can include headaches, dizziness, vision problems or confusion — cause CTE.
"We've had an inkling that subconcussive hits — the ones that don't [show] neurological signs and symptoms — may be associated with CTE," says Dr. Lee Goldstein, an associate professor of psychiatry at the Boston University School of Medicine and the lead investigator on the study. "We now have solid scientific evidence to say that is so."
And this evidence, he says, leaves researchers "terrifically concerned."
"The concussions we see on the ballfield or the battlefield or wherever — those people are going to get attention," Goldstein says, "because it's obvious they've had some sort of injury. We're really worried about the many more people who are getting hit and getting hurt — their brain is getting hurt — but are not getting help because we can't see the evidence on the outside that their brain is actually hurt. It's a silent injury."
Translating Goldstein's concern to the football field, Chris Nowinski, who heads the Concussion Legacy Foundation, says, "We see the hard hits all the time, where a guy pops up and smiles and [signals] a first down, and [we think], 'OK, that hit was fine.' But what this study says is: No, that hit probably wasn't fine, and that poor guy can't feel the damage that's happening in his brain right now."