NEARLY a fifth of US troops returning from the war in Iraq may suffer from post-traumatic stress disorder and other mental health problems, but many are not seeking treatment, according to a study released on Wednesday.

The study, published in last week's New England Journal of Medicine, is one of a very few that have examined the psychological impact of war so close to the time of deployment. It has already begun to reshape how soldiers are treated, both in the field and after they return home, researchers said.

Specifically, the study was partly aimed at gauging the psychological barriers - from concern about the stigma associated with mental illness to fear of possible harm to one's career - that keep troops from seeking help for combat-related stress disorders.

"There are a significant number of soldiers who need or require help," study co-author Carl Castro of the Walter Reed Army Institute of Research said in an interview.

Castro and his colleagues studied members of four US combat infantry units using an anonymous survey administered either before deployment to Iraq or three to four months after their return from combat duty. Troops who served in Afghanistan were also included in the survey.

The rate of post-traumatic stress disorder was 5 per cent among the 2,530 Army infantry soldiers headed to Iraq, but it rose sharply following deployment, the researchers found.

The rate of the disorder was nearly 13 per cent among 894 soldiers who returned from eight months of duty in Iraq. It was more than 12 per cent for 815 Marines who served six months there, and about half that for 1,962 infantry soldiers who returned from Afghanistan. The surveys were done in 2003.

In contrast, the rate of long-term post-traumatic stress disorder among Viet Nam War veterans years after their return has been 15 per cent, and between 2 per cent to 10 per cent among veterans of the Gulf War. It averages around 3 per cent to 4 per cent in the general population.

Not seeking treatment

The study found that only 23 per cent to 40 per cent of those suffering from mental health problems had sought help, with many admitting they feared seeking treatment would make them appear weak or make their peers treat them differently.

"Concern about stigma was disproportionately greatest among those most in need of help from mental health services," the study's authors said.

Other mental health problems examined include major depression and generalized anxiety, the study said.

Not surprisingly, the team discovered a direct relationship between the likelihood of post-traumatic stress and combat.

The illness rate was 4.5 per cent for soldiers not involved in shooting and jumped to than five fire fights.

In general, the Afghanistan troops had fewer mental health problems, but they were less likely to see serious action.

Just 1 per cent of the troops who had been in Afghanistan said they were responsible for the death of a civilian, versus 14 per cent of Army soldiers in Iraq and 28 per cent of Marines who served in Operation Iraqi Freedom.

In a journal editorial, Matthew Friedman of the Department of Veterans Affairs said there is concern that the prevalence of post-traumatic stress disorder will increase in coming years because the disorder can take a few years to surface.

"It may simply be too early to assess the eventual magnitude of the mental health problems related to deployment to Operation Iraqi Freedom or Operation Enduring Freedom," Friedman said.

(Agencies via Xinhua)