With more American women fighting—and dying—for their country than ever before, psychologists are exploring how they may fare differently from their male counterparts. The emerging psychological research presents a mixed and still incomplete picture, but has yielded some interesting findings.

For one, psychologists have found that women who experienced sexual harassment or trauma before or during their military service are more likely to suffer post-traumatic stress disorder than those who were not sexually traumatized. And on a more hopeful note, psychological research finds that female soldiers in combat may be more resilient to its effects than male soldiers.

The research is continuing, both to understand the prevalence of sexual assault among women serving and to determine whether exposure to combat affects men and women differently, says Amy Street, PhD, a researcher with the Department of Veterans Affairs. Ultimately, understanding those differences should help researchers and practitioners design effective interventions for both men and women.

"It really informs us about the type of treatment programs we need to create," Street says.

Expanding roles

Women have served in all the nation's wars, but today make up a larger percentage of the service than in previous conflicts. According to the latest data available from the Defense Manpower Data Center, as of September 2008, women made up 14 percent of the U.S. active-duty force, a number that's grown from 2 percent in 1973.

In addition, out of the 1.6 million service members who have deployed to Afghanistan and Iraq since 2001, more than 200,000 were women.

"Women are into almost all jobs, and at every rank, so it's a lot harder to operate without them," says Lory Manning, who directs the Women in the Military Project for the Women's Research and Education Institute in Washington, D.C.

One area of focus has been PTSD among women. Looking at it one way, women who enter military service may start at a disadvantage when it comes to experiencing PTSD, because compared with men, nearly twice as many civilian women report PTSD than civilian men, according to a review of 25 years of research on sex differences in trauma and PTSD published in Psychological Bulletin (Vol. 132, No. 6, pages 959–992).

But does that mean women are more likely to have PTSD after serving? Not according to research by Army Col. Carl Castro, PhD, a principal investigator with the Walter Reed Army Institute of Research. He followed two groups of women who deployed to Iraq in 2004. Compared with male soldiers with similar jobs and comparable exposure to violence, women soldiers did not show elevated levels of PTSD during and three months after their deployments.

So, says Castro, while women start out with more PTSD than men, the growth rate for men is steeper than the increase for women. "I'm often asked, 'Well, why aren't women higher?' and all I can say is, 'They're not!'" he says. "I think we ought to be highlighting how well female soldiers are doing in a combat environment."

Meanwhile, University of Michigan researchers Penny Pierce, PhD, and Lisa Lewandowski, PhD, are studying the impact that deploying to Iraq and Afghanistan has on the physical and mental health of Air Force women. Along with co-investigator Amiram Vinokur, PhD, they oversee The Women Veterans Project, an extensive collection of longitudinal data on the mental and physical health of military women. The project started studying the post-deployment adjustment of women Persian Gulf War veterans in 1992.

Preliminary results from 1,114 Air Force women participants recruited in late 2004 show that women who report high work-family conflicts also report more symptoms of PTSD and depression. Compared with women who report less conflict with the work-family balance, these women also experience problems in their roles as family members and emotional functioning, which Pierce describes as getting along with loved ones, voicing emotional needs, handling disagreements, and keeping households running smoothly.

People struggling with role and emotional functioning are usually experiencing difficulties at work, too, Lewandowski says.

"When we see effects on role and emotional functioning, it's problematic because then you start to lose social support, and those supports are where people find self-esteem and confidence in life," Pierce says.

They also found that lower-ranking women who deployed to the theater of war in and around Iraq or Afghanistan reported poorer health outcomes then women who deployed elsewhere, Pierce says.

Working from the study's results, Lewandowski and Pierce want to design interventions that will help all service members reduce work-family conflicts, while still acknowledging that what makes deployments hard—separation from family, long hours, physically demanding work in tough conditions—can't be made easier.

"We can't change the nature of war," Lewandowski says.

Sexual harassment

Other research points to the role sexual harassment and sexual trauma may have in a woman's chances of developing PTSD. In one study, Rachel Kimerling, PhD, of the VA's National Center for PTSD and the Center for Health Care Evaluation examined the electronic health records of 125,000 Iraq and Afghanistan veterans who came to VA facilities for health care between September 2001 and October 2007. She found that both women and men who had screened positive for military sexual trauma were more than one-and-a-half times more likely to be diagnosed with a mental health condition compared with veterans who experienced no such trauma, according to findings presented at an American Public Health Association conference in October 2008.

"Anecdotally, the clinicians I work with describe it as the double whammy, and they're seeing increased numbers of men and women who've experienced both types of trauma," Kimerling says.

A similar finding has emerged through the Millennium Cohort Study, which is tracking the long-term mental and physical health of 150,000 service members across all branches of the military, including active-duty, Guard and Reserve. The Department of Defense-funded study recruited three panels of participants in 2001, 2004 and 2007. Researchers asked participants about their physical and mental health when they enrolled in the study, and will continue to follow them every three years until 2022.

The study found that men and women who at baseline reported prior assault were twice as likely to report PTSD symptoms after their deployment than those who hadn't been assaulted (May 2008 issue of Epidemiology, Vol. 19, No. 3).

Before the results, researchers hypothesized that service members who'd experienced assault—but were now part of the military—could be more resilient to future stressful events, says Tyler Smith, PhD, an epidemiologist serving as principal investigator at Naval Health Research Center, San Diego.

"We did not find that," Smith says.

The link between PTSD and previous sexual trauma may be a particularly important finding since sexual harassment and assault continue to be a significant problem in the military for women and men. One in five women veterans who seek health-care services from the Department of Veterans Affairs reported experiencing military sexual trauma, an incident of sexual assault or severe harassment while in uniform. These women were more than eight times as likely to be diagnosed with PTSD as compared with women who did not report these experiences, according to a study published in December 2007 in the American Journal of Public Health (Vol. 97, No. 12).

The study found that men who reported military sexual trauma were three times as likely to be diagnosed with PTSD, as compared with men who did not report that experience.

Given these study results, sexual trauma and harassment need to be considered as potential risk factors for women who serve in the military—and clinicians have to be ready to respond effectively, Kimerling says.

"We want to see evidence that knowing all these things, knowing how to detect, knowing how to provide evidence-based care is, in fact, having a positive impact for newly returning veterans," she says.

Looking to the future, Street is working with her colleagues at the National Center for PTSD to launch a study this year surveying 4,000 soldiers and Marines, half of them women, about sexual trauma, experiences in Iraq and Afghanistan and mental health outcomes.

"It's so we can both characterize the experiences of women, relative to their male counterparts, and their current well-being," Street says.