Are women Veterans more susceptible to developing posttraumatic stress disorder than their male counterparts? And if so, why?
“In the general population, women are twice as likely as men to develop posttraumatic stress disorder,” noted Dr. Sonja Batten, VA’s Deputy Chief Consultant for Specialty Mental Health. “But among recent returnees seeking care at VA, PTSD rates among men and women are the same. Statistics such as these suggest the need to better understand the role of gender in PTSD, particularly as it may impact our Veterans seeking care.”
Researchers at the Department of Veterans Affairs are now taking some initial steps toward understanding this complex subject. To that end, Dr. Sabra Inslicht, a staff psychologist at the San Francisco VA Medical Center and an assistant professor of psychiatry at the University of California, San Francisco recently led a VA study that took a closer look at how men and women learn to fear. Her work was published in the October 2012 issue of the Journal of Psychiatric Research.
“If we can learn more about potential gender differences in the process of fear learning,” Inslicht said, “it may help us develop more targeted treatments that are geared more precisely to the unique needs of men and women.”
For their study, Inslicht and her team recruited 18 men and 13 women who had been diagnosed with PTSD. These participants were all shown various images on a computer screen. Electrodes were attached to their palms so researchers could measure participants’ physiological response to each image.
After certain images appeared, the test subject received a small electrical shock. Gradually, the test subject came to associate these particular images with something unpleasant.
“They learned to anticipate the impending shock,” Inslicht said. “They learned the danger cues. We call this ‘fear conditioning.’”
Researchers carefully monitored test subjects’ skin conductive responses — that is, how sweaty their palms got — to measure the body’s stress reaction to the image on the screen.
“We discovered that women responded more strongly to the visual cues than men when they saw a particular image that they knew was going to be followed by an electric shock,” Inslicht explained. “This suggests that women conditioned more robustly than men. In our future work, we’d like to get a better understanding as to why these differences may occur.”
Understanding possible gender differences more precisely could put us in a position to develop much more effective, focused therapies for PTSD
“To some extent, learning to fear is important for survival,” the researcher said. “When we are threatened by something dangerous, we tend to react with a stress response or ‘fight-or-flight’ response. It helps keep us safe by mobilizing our bodies to either fight or flee a threat, thus enabling us to protect ourselves from harm in dangerous situations.”
Inslicht said this ‘fight or flight’ response, however, can sometimes persist even in non-threatening situations.
“For example,” she said, “if you witnessed a suicide bombing while on patrol in a crowded marketplace in Afghanistan, you might develop a fear of crowded places. While you’re on patrol and in potential danger, a heightened level of vigilance can be protective. However, if that response persists even after returning home and to a safe place, it can become problematic.
“When you’re unable to turn it off in safe situations, the stress becomes prolonged,” she continued. “This can cause wear and tear on both the mind and the body. When this heightened reactivity starts to negatively impact your daily life, we begin to worry about posttraumatic stress.”
But if fear conditioning does, in fact, occur differently in men and women, then might not the process known as ‘fear extinction’ also be affected by gender differences?
“Fear extinction happens,” Inslicht said, “ when you are gradually exposed to the previously learned danger cues, such as crowds, and you gradually come to realize that the cue will not be followed by a stressful or potentially traumatic event. This results in the diminishing of the fear response. Since extinction learning is believed to be important for recovery from PTSD, a deeper understanding of this process could alter our strategy for how we treat PTSD in men and women.”
Inslicht said her small study leaves a number of questions unanswered, and that more in-depth research is needed.
“For example, all our study participants had PTSD,” she said, “so we couldn’t arrive at any conclusions regarding whether women, as a general rule, condition more strongly than men do, or whether this difference is found only among women who have already developed PTSD.”
“Finally, we did not examine what may drive the gender differences that we found,” the researcher noted. “For example, there may be biological differences such as particular hormones and neuropeptides that may mediate these effects.”
Inslicht said the research community is only just beginning to understand fear learning and extinction mechanisms and their relationship to PTSD.
“Ultimately, however, this line of research may result in advances for treatment,” she concluded. “There may be ways that we can enhance extinction learning — perhaps through medications or with other modifications to existing behavioral treatments.”