dr. anne mckee, the chief neuropathologist at the boston v.a. >> reporter: when dr. e autopsied patriots tight end eron hernandez, who killed kmself after being convicted of r rder, she found the most unvere case of c.t.e. ever in someone under 30. now she's seeing a similar a ttern in deceased veterans who experienced a different kind of head trauma-- combat blasts. of the 102 veterans' brains dr. mckee's examined, 66 had c.t.e. how is it that combat veteran, who maybe just experienced a blast, has the same type of injury? >> this blast injury causes a tremendous sort of ricochet or a whiplash injury to the brain inside the skull. had that's what gives rise to the same changes that we see in football players, as in military veterans. >> reporter: blast trauma was first recognized back in world war i. teown as "shellshock" poorly protected soldiers often died immediately or went on to suffer physical and psychological symptoms. waday, sophisticated armor allows more soldiers to walk away from an explosion, but exposure can still damage the brain, an injury that can wo

dr. mckee's work with testing on mice. >> dr.'re in the neuro-tunnel laboratory. >> alfonsi: inside his boston university lab, dr. goldstein built this 27-foot blast tube where a mouse, and in this demonstration, a model, is exposed to an explosion equivalent to the i.e.d.s used in iraq and afghanistan. >> goldstein: when it reaches about 25, this thing is going to go. ( explosion ) >> alfonsi: dr. goldstein's model shows what's going on inside the brain during a blast. the brightly-colored waves illustrate stress on the soft tissues of the brain as it ricochets back and forth within the skull. >> goldstein: what we see after these blast exposures, the animals actually look fine. which is shocking to us. so, they come out of what is a near-lethal blast exposure, just like our military service men and women do. and they appear to be fine. but what we know is that that brain is not the same after that exposure, as it was microseconds before. and if there is a subsequent exposure, that change will be accelerated. and ultimately, thi

and when dr. mckeeriots tight-end aaron hernandez, who killed himself after being convicted of murder, she found the most severe case of c.t.e. ever in someone under 30. now, she's seeing a similar pattern in deceased veterans who experienced a different kind of head trauma-- combat blasts. ( explosions ) of the 102 veterans brains dr. mckee's examined, 66 had c.t.e. i can understand a football player who keeps, you know, hitting his head, and having impact and concussions. but how is it that a combat veteran, who maybe just experienced a blast, has the same type of injury? of ricochet, or a whiplash injury to the brain inside the skull, and that's what gives rise to the same changes that we see in football players, as in military veterans. >> alfonsi: blast trauma was first recognized back in world war one. known as "shell shock," poorly protected soldiers often died immediately or went on to suffer physical and psychological symptoms. today, sophisticated armor allows more soldiers to walk away

of the 102 veterans brains dr. mckee examined, 56 had c.t.e. >> how is this it that combat veteran who maybe just experienced a blast has the same type of injury. >> this blast injury causes a tremendous sort of ricochet or a whiplash injury to the brain inside the skull and that is what gives rise to the same changes that we see in football players as in military veterans. >> reporter: blast trauma was first recognized back in world war i. known as shellshock, poorly protected soldiers offer be died immediately or went on to suffer physical and psychological symptoms. today sophisticated armor allows more soldiers to walk away from an explosion but exposure can still damage the brain. an injury that can worsen over time. >> it is not a new injury. but what has been really stumping us, i think, as physicians is it's not easily detectable, right. we've got a lot of psychiatric symptoms and you can't see it very well on images of the brain. so it didn't occur to us. and i think that has been the gap, really, that this has