A report on the new findings appeared in the journal Science Friday and could have implications for veterans of the Iraq war.

The original research studied 1,200 veterans and concluded that 15.2 percent had long-term PTSD, while 30.9 percent had suffered PTSD at some point in their lives, often long after the war, said The New York Times. The new figures are 9.1 percent and 18.9 percent.

Symptoms of PTSD include flashbacks, emotional numbness, hypervigilance and exaggerated startle responses.

Lead author Dr. Bruce Dohrenwend, a psychiatric researcher at Columbia University and the New York State Psychiatric Institute, said despite the lower figures a substantial number of veterans, about a quarter of a million, were suffering PTSD.

Veterans groups criticized the study, which they say used criteria that was too narrow, and say it could threaten funding for veterans' mental health.

The Department of Veterans Affairs spends almost $10 billion a year on benefits and mental healthcare services for veterans diagnosed with the disorder.