Two weeks before his second deployment to Iraq last September, Army Specialist Michael DeVlieger broke down.
"At first, I thought it was something that everybody experienced," DeVlieger told ABC's Bob Woodruff, "and just through time and perseverance I guess it would pass." It didn't pass.
After an 11-day hospitalization, DeVlieger was given a diagnosis of major depressive disorder, three psychiatric prescriptions -- and deployment orders.
"Eighteen hours after he got out of the hospital, he deployed to Iraq," DeVlieger's wife, Christine DeVlieger, recalled. He left for Iraq despite Pentagon policy requiring that service members establish three months of "stability without significant symptoms" before deploying.
"I was a ticking time bomb," Michael DeVlieger said.
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Citing privacy, officials at DeVlieger's base in Fort Campbell, Ky., declined to comment except to say there was a combat stress unit assigned to DeVlieger's base in Iraq.
More than 600,000 Americans have served multiple tours in Iraq and Afghanistan.
"Psychological trauma is cumulative," explained Dr. Paul Ragan, a former Navy psychiatrist who is an associate professor of psychiatry at Vanderbilt University. More deployments can mean more mental stress, and for some, more mental illnesses, he said.
Army surveys show that for those soldiers deployed once, the rate of anxiety, depression and post-traumatic stress disorder is 12 percent. For those deployed three or more times, the rate is 27 percent.
"People who have psychiatric symptoms, actively symptomatic with PTSD or depression, are being sent back to the very situation that caused their PTSD and depression," Ragan said.
The Army's chief psychiatrist, Dr. Elspeth Ritchie, agrees with the Rand Corp.'s estimate that 300,000 service members have demonstrated post-traumatic stress disorder symptoms. Some are returning to the battlefront, although the Army is not keeping track of how many.
"I certainly would not want to lump all soldiers who have experienced post-traumatic stress disorder and say they are impaired and not able to do their job," Ritchie told Woodruff. "I think that would be very stigmatizing."
Many soldiers, as Ritchie points out, receive treatment and cope successfully with PTSD or depression.
"We have a number of reasons for sending the soldiers back to war -- we have a mission, clearly," Ritchie said.
The mission asks a lot of a few. Less than 1 percent of the population serves, and serves again.
"We know the Army is stretched too thin. We know how busy we are. We know we need more forces," Ritchie said.
While Ritchie said she was unfamiliar with the details of DeVlieger's case, she added that if it were true, it "clearly violates our policy." Ritchie said the Army works hard to screen veterans, but there will always be some missed cases.
The military is increasingly medicating its warriors, and in some cases, returning them to the fight.
Ritchie defended the concept. "You have to remember, PTSD is a treatable disorder, and you can have symptoms and still do your job quite well."
Twelve percent of soldiers in Iraq and 17 percent of those in Afghanistan reported taking antidepressants, anxiety medications or sleep medications in the Army's most recent mental health survey.
The use of psychiatric drugs on the battlefield has not been scientifically studied, and some say the practice carries risks.
"The black box on the label talks about side effects like suicide, poor judgment," retired Army psychologist Bart Billings warned. "It's really not a good idea to put people in a battle situation where the side effects of the medications they're taking could be suicide -- when they're carrying weapons."
As a psychiatrist in Kuwait during the first Gulf War, Ragan saw a vastly different military opinion of psychiatric medications. "Clearly, in 1990, if someone was on antidepressant medication, we sent them back to the United States."
The Army has 200 mental health professionals in Iraq to treat soldiers and monitor medications. This number has remained constant since the start of the war, even as the number of troops has increased.
Former Marine Cpl. Michael Cataldi, an Iraq war veteran, remembers the dark days that followed his first deployment.
"I was taking anti-psychotics, narcotics for pain and drinking at least 30 beers a night," he said.
He came home to Camp Pendleton, Calif., haunted by the horrors of war, including a helicopter crash that killed 30 fellow Marines.
"I saw a Marine Corps sergeant who had the majority of the top of his head missing, and he had the look of a scream on his face," Cataldi recounted. "And that stuck with me, and it still sticks with me."
Cataldi said he went to see a military psychiatrist who brushed aside his concerns. "I tell them, `I'm having nightmares. I feel like I'm having out-of-body experiences. I feel like I'm watching myself in a movie. I'm losing memory, coordination.' This whole time he said, `You're not feeling that way.' Exact words: `No, you're not.'"
Cataldi was prescribed several psychiatric medications and deployed to Iraq for a second tour of duty.
When asked for comment, Marine public affairs officer Cpt. Carl Redding told ABC News that Cataldi's records were "private and not releasable." Redding continued, "Marines with a psychiatric disorder in remission or those whose residual symptoms do not impair their duties may be considered for deployment."
Cataldi's wife, Monica Cataldi, believes the decision was wrong. "In my opinion, anybody who has to be on medication just to function, just to do their job, shouldn't go to Iraq."
A month into his second tour in Iraq, Cataldi said he ran out of his psychiatric medication.
"I went cold turkey on a narcotic in a combat zone," Cataldi said. "I woke up lying in the dirt in the middle of the night. I don't remember how I got there, with my rifle buried next to me."
"I wasn't mentally safe. I was a liability. I could have got someone hurt," Cataldi said.
Redding emphasized the military's focus on mental health. "Providing proper mental health care and assessing mental fitness to deploy are of the highest importance to Marine leaders."
Last fall, Sgt. Chad Barrett stood before an Army medical evaluation board in Fort Carson, Colo., and asked to return to Iraq, even though his medical record included a PTSD diagnosis, a suicide attempt and a commander's recommendation that he be "removed from the United States Army and receive the treatment he needs."
On Christmas Day last year, the Army sent Barrett to Iraq for the third time. He never came home.
"This was a slow, progressive mental illness that never would have come about had he not been deployed repeatedly in a short period of time, had he gotten the care that he needed, had he gotten the best that the Army had to offer," said Chad's widow, Shelby Barrett.
A month into his third tour, 35-year-old Chad Barrett committed suicide in his barracks. He overdosed on the medications the Army had prescribed to help him cope.
Officials at Fort Carson, citing privacy, said they could not comment on Barrett's death.
"In a body bag is not how I wanted my husband back," said Shelby Barrett.
The most recent Army Suicide Event Report showed suicides climbed to the highest number on record last year. Half of those who committed suicide had visited a medical program or clinic within 30 days of death and twenty-seven percent had a history of psychiatric medication.
ABC News looked into a dozen suicides that followed multiple deployments and had showed clear signs of mental distress.
In February 2007, Army Sgt. Brian Rand took his life in the park in Clarksville, Tenn., where he had been married a year before.
"He shot himself in the head," Rand's widow, Dena Rand, told Woodruff. "It was like a nightmare."
Dena Rand has paperwork showing that her husband sought mental health care and was referred to the mental health department during his second tour in Iraq. But nothing ever came of it.
"He knew he needed help, and he tried and he wasn't very successful," Rand said.
In a physical exam for discharge from the military, a psychiatrist wrote that Brian Rand was "mentally unsound."
"Someone got that report showing that my husband was mentally unsound. Someone should have notified his chain of command, or at least myself," said Rand. "I want to know who dropped the ball."
For more information, visit the Army's 'Battlemind' program for mental health: www.battlemind.army.mil