A study released early last month suggests there might be a link between hormone levels and the risk for post-traumatic stress disorder.

The new findings by researchers at the University of Texas at Austin are part of the Texas Combat PTSD Risk Project, which aims to identify biological, psychological and environmental vulnerability factors that predict the emergence of PTSD. Ten to 18 percent of Iraq and Afghanistan veterans are likely to have PTSD after they return, according to the Department of Veterans Affairs.

The UT researchers examined the hormone levels, specifically cortisol and testosterone, of 120 U.S. soldiers before they deployed to Iraq.

The soldiers underwent a stress-inducing carbon dioxide challenge, in which they breathed in carbon dioxide, robbing their bodies of oxygen. That acute and short-lived suffocation experience can lead to an array of reactions from euphoria to full-on panic, said Bob Josephs, lead author of the UT study.

Researchers, by obtaining hormone data from saliva samples from the soldiers, measured the change in testosterone and cortisol levels before and after the test. They found that soldiers who exhibited no or little change in those levels were more likely to later show symptoms of PTSD.

Soldiers with elevated levels of testosterone or cortisol were less likely to develop symptoms of PTSD.

"These soldiers for some reason — and nobody knows why this is — they have this really powerful testosterone response that we think blunts the experience of fear and thus doesn't allow these stressors to conspire to produce the disease," Josephs said.

A nearly 30-year-old study first showed a connection between abnormal cortisol levels and an increased risk for PTSD. But in the years since, research on the topic has been inconsistent. And no one had looked at the role testosterone might play, according to Josephs.

"We're really, really excited about this and what's nice is that we see these clear and obvious pathways to treat individuals who are in positions that expose them to these kind of extreme stressors, such as soldiers, first responders, those kinds of folk," Josephs said.

In addition to the carbon dioxide challenge, soldiers, while in combat, filled out monthly surveys, responding to questions such as "did you experience this stressor in the past month?" That enabled researchers to look at symptoms of PTSD and combat stressors over time.

The researchers have developed a fast-acting, powerful testosterone nasal spray. Josephs called it the Viagra of hormones, saying the spray works very quickly and lasts about four hours. He and the other researchers would like to secure grant funding to test the effectiveness of the spray.

"If we have individuals who are regularly or occasionally exposed to stressors that have the potential to induce PTSD, can they, by self-administering this nasal spray, achieve the protection that we now see in people who have natural elevations in testosterone in response to stress?" Josephs said.

While testosterone can lead to hyper-sexuality and more aggression in people who are on testosterone replacement therapy, usually producing higher levels for sometimes years, the effects of the nasal spray are short term.

Josephs said he's eager to reach out to the Department of Defense to see if it is interested in collaborating with him on the research.

j.bergman@theday.com