"Half the population we brought in had no obvious impairment whatsoever," Nauman said. But when the Purdue group compared the in-season scans with the preseason scans, "we saw even more significant neurophysiological changes than in the players diagnosed with concussions."
Nauman and other researchers aren't exactly sure what is happening to these players. But they believe that what we call concussions are only one of several kinds of head injury that affect players' verbal ability, memory, and "vestibular system," which controls spatial orientation and balance. Many of the hits that produce "shell-shock" concussions involve blows to the side of the head, as happens with helmet-to-helmet collisions in the open field. The new group of injured players—the ones without visible injury—had suffered damage to the frontal lobe, the part of the brain that controls high-end "executive functioning."
"These seem to result from repetitive blows to the top-front of the head," Nauman told me in an e-mail. "Most common when players lead with their heads to block or tackle. The challenge is that we don't really have sideline tests that can evaluate visual working memory or impulse control. So it is very hard to find the players in this group. Our fear is that they go undiagnosed, keep playing, and accumulate more and more damage."
To avoid running afoul of physicians who believe that all football concussions can be diagnosed on the sidelines, the Purdue researchers are not calling the new kind of brain injuries concussions. They are calling them impairments. But medical turf wars aside, it seems obvious these injuries are concussions, too.
Nauman thinks that while football helmets are pretty good at protecting against skull fractures, they are not good at protecting against concussions. And overconfidence in the helmets' protective power prompts many NFL athletes to deliver and accept hits that would have killed the helmetless players of previous generations.
"If you have traumatic brain injury and keep playing, you are at enormous risk for really serious damage later on," Nauman said. "Because these kids don't show any symptoms, they keep playing and exposing themselves to neurological trauma."
The neurological changes observed by the Purdue researchers did subside in the postseason. As good as brain scans are, they measure only indirectly what is happening at the neural level. And, as with all science, the findings of the Purdue team need to be expanded and independently verified. So we're likely to remain uncertain about the exact nature of this new class of injuries, their behavioral implications, and how they translate to measurable deficits later in life.
While acknowledging those uncertainties, Nauman told me he would never allow a child of his to play football. And now that I've seen the pictures of brain changes among "concussion-free" players, I would no more let a school-age child of mine play competitive football than I would let him or her start smoking. At least one prominent football commentator has said the sport is not for his own son. What does it say about us that we derive so much enjoyment from watching other people's kids take risks we would never accept for our own?
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