The study, released Thursday, was based on the department health records of 289,328 veterans involved in the two wars who used the veterans health system for the first time from April 1, 2002, to April 1, 2008.
The researchers found that 37 percent of those people received mental health diagnoses. Of those, the diagnosis for 22 percent was post-traumatic stress disorder, or PTSD, for 17 percent it was depression and for 7 percent it was alcohol abuse. One-third of the people with mental health diagnoses had three or more problems, the study found.
The increase in diagnoses accelerated after the invasion of Iraq in 2003, the researchers found. Among the group of veterans who enrolled in veterans health services during the first three months of 2004, 14.6 percent received mental health diagnoses after one year. But after four years, the number had nearly doubled, to 27.5 percent.
The study’s principal author, Dr. Karen H. Seal, attributed the rising number of diagnoses to several factors: repeat deployments; the perilous and confusing nature of war in Iraq and Afghanistan, where there are no defined front lines; growing public awareness of PTSD; unsteady public support for the wars; and reduced troop morale.
Dr. Seal said the study also underscored that it can take years for PTSD to develop. “The longer we can work with a veteran in the system, the more likely there will be more diagnoses over time,” said Dr. Seal, who is co-director of the mental health clinic for Iraq and Afghanistan veterans at the San Francisco veterans medical center.
The new report joins a growing body of research showing that the prolonged conflicts, where many troops experience long and repeat deployments, are taking an accumulating psychological toll.
A telephone survey by the RAND Corporation last year of 1,965 people who had been deployed to Iraq or Afghanistan found that 14 percent screened positive for PTSD and 14 percent for major depression. Those rates are considerably higher than for the general public.
“The study provides more insight as to just how stressed our force and families are after years of war and multiple deployments,” said René A. Campos, deputy director of government relations for the Military Officers Association of America. “Our troops and families need more time at home — more dwell time, fewer and less frequent deployments.”
The study was posted Thursday on the Web site of The American Journal of Public Health.
Dr. Seal cautioned that, unlike the RAND study, the results from her research could not be extrapolated to the roughly 1.6 million veterans who have served in Iraq or Afghanistan because about 60 percent of them were not receiving health care through the veterans system.
But she noted that the number of Iraq and Afghanistan war veterans receiving care through the veterans system was at a historic high, 40 percent, potentially making the study’s results more universal.
The study also found that veterans older than 40 with the National Guard or the Reserves were more likely to develop PTSD and substance abuse disorders than those under 25. A possible reason, Dr. Seal said, is that older reservists go to war from established civilian lives, with families and full-time jobs, making combat trauma potentially more difficult to absorb.
“It’s the disparity between their lives at home, which they are settled in, and suddenly, without much training, being dropped into this situation,” she said.
In contrast, the study found that among active-duty troops, veterans under 25 were more likely to develop PTSD and substance abuse problems than those over 40, possibly because those younger troops were more likely to have been involved in front-line combat, Dr. Seal said.