Story highlights

The living brains of two ex-soldiers show damage similar to that of football players who have committed suicide

Brain trauma is a "signature injury" of wars in Iraq and Afghanistan

Chronic traumatic encephalopathy, or CTE, has no cure

CNN  — 

After his last tour in Iraq, it took master gunner Shane Garcie about six weeks to notice he’d changed.

“Your brain is throwing parties because you’re home, you’re alive,” says Garcie. “So, it doesn’t settle in right away.”

Now he’s not sure what bothers him most: the fogginess of his brain, the anger that can erupt from nowhere or the deep, dark depressions he can’t shake off.

“One minute I’m in a good happy mood, everything is cool; the next minute I’m depressed,” Garcie told CNN chief medical correspondent Dr. Sanjay Gupta. “I don’t want to be around anybody, I want to isolate. Some days, I don’t want to get out of bed.”

“We could walk around this town and everybody, 90% of these people, would say, ‘Hey, Shane, hey,’ ” Garcie says about his hometown of Natchitoches, Louisiana. “But it’s not Shane. It looks like me, it walks like me, it talks like me, but it’s not me because of the damage.”

Since 1984, Green Beret Tommy Shoemaker has served in many war theaters – Kuwait, Iraq, Afghanistan, Somalia, Bosnia – and is still an Army reservist. He came home from Iraq to Monroe, Louisiana, in late 2006 with a bum leg and a disabled brain.

“I carry note cards and a pen with me everywhere I go, and when I’m talking to somebody, I write it down,” Shoemaker told Gupta. “Because if I don’t, I won’t remember. I mean memory was not a problem for me, I could remember anything. And now I have to write everything down.”

But it’s the mood swings he can’t control that do the most harm.

“I’ve always been really easygoing. Everything rolled off my back, no problems,” says Shoemaker in his Southern drawl.

“But now that’s not so. I mean, I’ll get mad over something as simple as a banana peel in the front yard or my wife saying the wrong thing to me, and is it really anything? No, but at that moment, it hits me and I just do things that I would’ve never done before. I yell, I scream, I holler, and that’s just never been my manner. I’m sad for my kids and my wife to have to live with that.”

“It’s tough, really tough,” agrees Pam Shoemaker, Tommy’s wife. “I do remember him telling me that ‘I’m different,’ ‘I’m not the same’” when he first came home. “I didn’t understand. But I do now.”

Brain studies

Dr. Julian Bailes, co-director of the NorthShore Neurological Institute in Evanston, Illinois, is pointing at the angry red and vivid yellow blooms on the PET scan of a living brain.

“Compared to normal controls, you see abnormal binding in the areas under the surface of the brain and deeper in the brain, showing abnormal accumulations of tau protein,” he explains.

All are signs of CTE, or chronic traumatic encephalopathy, a crippling neurological disorder caused by repeated blows to the head.

Characterized by deep depression, failing memory and anger that lurks just under the surface, CTE is a form of dementia that first came to light in the boxing world. “Punch drunk” was the term most often used for former pugilists, such as Muhammad Ali, who developed brain damage after a lifetime of hard knocks. Today it’s called dementia pugilistica and is considered a variant of CTE.

CTE is the disease many believe played a role in the deaths of former NFL players like Ray Easterling, Junior Seau, Shane Dronett and Dave Duerson. They all shot themselves. Duerson left a note asking that his brain be studied.