Since 2003, 425,000 Americans have served in Iraq. According to U.S. military medical experts, one in six returning veterans have reported problems with depression, anxiety or post-traumatic stress disorder.
Joshua Heppel works a security shift for a bar in Louisiana. He checks IDs and keeps the peace. Three years ago, the 26-year old was a soldier in Iraq.
"I suffered a shoulder injury while I was in Iraq," Heppel explains, "so I'm a little banged up still from it. But I'm trying to cope along."
That's the injury you can see. But mental health issues - including anxiety and depression - are among the top problems facing returning veterans. This wave of psychological difficulties has renewed interest in the harmful impact of war on the human mind, and it's the focus of a new study published August 2nd in the Journal of the American Medical Association.
Jennifer Vasterling, with the United States Department of Veterans Affairs, is the lead author of the new study. She says she and her colleagues compared the brain function of 600 soldiers returning from Iraq with 300 soldiers on active duty who did NOT serve in the war zone.
"We had a mixed pattern of findings," Vasterling says. "On some measures we saw no changes, but on other measures, especially on specific measures of memory and attention, we saw a negative effect of deployment."
For Iraq war veteran Josh Heppel, the adverse effects of combat were offset somewhat by the one very positive thing he'd acquired on the battlefield -- quick reaction time.
"You have to have a heightened awareness of what was going on in your surroundings," Heppel says, "because you didn't know what was going to happen. That's the only way you can survive, really."
But study author Jennifer Vasterling says her research shows this battle mind-set is also associated with targeted aggression, guarded emotions and the inability to relax -- behaviors that could make civilian life miserable for the returning veteran.
"I think what time will tell is whether this pattern remains the same and whether the advantage that we see in response time remains a true positive or turns into something else in the long run."
Vasterling says the study highlights the importance of programs that help returning soldiers transition back to home life. And it points as well, she says, to the need to carefully monitor the mental health and the day-to-day functioning of soldiers still serving on the front lines.