A bomb-sniffing dog from the U.S. Air Force is led by a soldier with the U.S. Army 25th Infantry Division. The pair are seen searching for IEDs during a raid in Iraq in 2006. Photo by U.S. Air Force

BOSTON, Dec. 29 (UPI) -- A new study suggests the insurgency phase of the Iraq War caused an uptick in instances of post traumatic stress disorder, or PTSD.

The research was conducted by scientists at the National Center for PTSD, a collaborative effort between the VA Boston Healthcare System and the Boston University School of Medicine.


To better understand which characteristics of modern warfare in the Middle East are most associated with PTSD, researchers split the Iraq War into three distinct phases -- the initial invasion, the insurgency and the surge. The insurgency was marked by a greater use of guerilla-style tactics, including suicide attacks and roadside bombs.

When they used these phases to analyze the mental health diagnoses of Iraq War veterans, they found men deployed during the insurgency phase were more than twice as likely to have developed PTSD. The same correlation was not found among women.

Researchers published their findings in the journal Psychological Trauma: Theory, Research, Practice, and Policy.

"Assessment of the nature of combat may be useful in research and in clinical settings," researchers wrote in their paper.

But more research is need to determine what specifically about the insurgency phase may be responsible for the surge in PTSD rates.