(USA Today) -- Multiple combat deployments to Iraq are increasing serious mental health problems among soldiers, triggering drug and alcohol abuse and appear to contribute to record suicide levels, say reports out Thursday at the American Psychological Association meeting in Boston.

In a typical unit headed to Iraq, 60% are on their second, third or fourth deployment, lasting about a year each, said Army Col. Carl Castro, who directs a medical research program at Fort Detrick, Md.

More time in Iraq means heavier exposure to violence, which leads more soldiers to develop symptoms of post-traumatic stress disorder and depression, Castro told attendees. By their third tour, more than a quarter of soldiers show signs of mental problems, and it's about one out of three for those exposed to heavy combat, according to a U.S. Army Surgeon General report in March.

In another report Thursday, deployment correlated with heavier drinking and illegal drug use, according to an anonymous survey of about 34,000 active-duty troops, reservists and National Guard members. Deployed reservists had the highest traumatic stress symptoms and rates of "seriously considering suicide," a Pentagon-funded study by RTI International found.

National Guardsmen and reservists sent to Iraq and Afghanistan are disproportionately represented in returning vets' suicides, a Department of Veterans Affairs analysis found. There were 115 Army suicides and 935 reported attempts in 2007, a record high, Army records show. "There are concerns about the Reserves," said Lynn Pahland, a health promotion policy director in the Defense Department. The military is increasing efforts to prevent, identify and treat troubled troops, she said.

About 75% of the 400 calls a week to a veterans crisis hotline come from Reserve and National Guard troops or their families, said Shad Meshad, president of the National Veterans Foundation, which runs the line.

On Wednesday, a Texas reservist going to Iraq for the fourth time called "in a hysterical state," Meshad said. His house was being foreclosed on, and his wife was taking the kids and leaving him. "We're just trying to help him out with the financial stuff and keep him from hurting himself."

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