The first empirical study of whether female combat veterans are more susceptible to post-traumatic stress disorder than their male counterparts is being funded with a $2.2 million grant from the U.S. Department of Veterans Affairs, Yale University announced Wednesday.

The nationwide study will for the first time investigate speculation that women are more vulnerable to PTSD. That premise presupposes women on average enter the military having had more civilian trauma than men and may suffer trauma from comrades and may have more stressors in combat zones than male veterans.

Of the 2 million Americans who have served in Afghanistan and Iraq since 2001, approximately 230,000 have been women, who are assigned to support roles in combat zones. Despite that, an unprecedented number of women have been in actual combat, making female veterans of these wars the largest cadre of U.S. military women exposed to warfare in history.

The collaborative study includes researchers from the VA, Women's Health Research at Yale and the University of Connecticut.

The study grew out of a $15,000 pilot grant awarded to Carolyn M. Mazure, director of Women's Health Research at Yale, by the Grace J. Fippinger Foundation.

The pilot study, which began in September 2009, recruited men and women combat veterans. It generated necessary feasibility data for a large, comprehensive proposal that earned the multi-million dollar grant to fund the nationwide study.

First Published: November 12, 2010, 5:00 a.m.