A survey of troops returning from the Iraq (search) war found 30 percent had developed mental health problems three to four months after coming home, the Army's surgeon general said Thursday.

The problems include anxiety, depression, nightmares, anger and an inability to concentrate, according to Lt. Gen. Kevin Kiley (search) and other military medical officials. A smaller group, usually with more severe cases of these symptoms, is diagnosed with post-traumatic stress disorder (search), or PTSD.

The 30 percent figure is in contrast to the 3 percent to 5 percent diagnosed with a significant mental health issue immediately after they leave the theater, according to Col. Elspeth Ritchie, a military psychiatrist on Kiley's staff. A study of troops who were still in the combat zone in 2004 found 13 percent experienced significant mental health problems.

Soldiers departing a war zone are typically given a health evaluation as they leave combat, but the Army is only now instituting a program for follow-up screenings three to six months later, said Kiley, speaking to reporters.

A pilot program for the follow-up screenings, conducted on 1,000 U.S. soldiers returning from Iraq to Italy last year, found a much greater incidence of mental health problems than expected, a fact Kiley attributed to post-combat stress problems taking time to develop once the danger has passed.

Only about 4 percent or 5 percent of troops coming home from combat actually have PTSD, but many others face problems adjusting, Kiley said.

The stress of combat, seeing dead and mutilated bodies, and feeling helpless to stop a violent situation are common triggers. In Iraq, truck drivers and convoy guards are developing mental health problems in greater numbers than other troops, Ritchie said, suggesting the long hours on the road, constantly under threat of attack, are taking their toll.

In Iraq, the military has about 200 mental health experts, grouped in what the Army calls "combat stress control teams." These teams are at many posts around the country and talk with troops after battles, try to prevent suicides and diagnose troops who should be evacuated from of the country because of mental health problems.

"They are worth their weight in gold," Kiley said of the teams.