Battlefield psychologists investigate stress in combat and after

In a new study in the American Journal of Psychiatry, Prof. Yair Bar Haim of TAU's Department of Psychology reports that people confronted with acute stress -- daily rocket attacks -- tend to dissociate from threats instead of becoming more vigilant. This research overturns accepted convention and may lead to better understanding of the mechanisms underlying acute stress reactions, he says.

Though conducted on the battlefields of the Middle East, Prof. Bar Haim's research has immediate repercussions for U.S. soldiers as well. "The American government is dealing with large numbers of soldiers coming home from Afghanistan and Iraq suffering from PTSD," he says. "Our study is important because it's the first to show the effects of war-related acute stress in real time." It also has significant implications for the understanding of other known PTSD triggers, such as rape or motor vehicle accidents.

A real-time picture of stress

Using fMRI and other imaging techniques, Prof. Bar Haim investigated neural mechanisms related to anxiety disorders and how people respond cognitively to stress. He also studied how people process threats when they are under severe stress. His previous studies, both at Tel Aviv University and through the U.S. National Institutes of Health, looked at neural, genetic and molecular factors related to threat processing in the brain, and these gave Prof. Bar Haim and his team a context to infer what happens in the brain when behavioral data on acute stress situations is collected.

In the most recent study, he looked at Israelis close to the firing zone, near the border with Gaza, where they had been living with the daily stress of rocket threats for eight years. The threat became more severe during the war. While his test subjects completed various computer tasks to test behavior, Dr. Bar Haim monitored processes at the deeper, unseen levels of the brain.

He found that subjects under acute stress developed symptoms of post-trauma and most often manifested a dissociative state rather than one of hypervigilance. Most important for clinical applications, the researchers found that the symptoms produce a measurable effect -- a neuromarker -- that may be used to predict who are the individuals most at risk for developing chronic PTSD following a traumatic event.

Less vigilant to personal threats

Prof. Bar Haim says this is the first study in the scientific literature to describe real-time effects of war-related stress on its victims. In the previous literature, scientists assumed that people under stress would become more vigilant to threats, rather than disengaging. "This calls for some revision of the foundations of the stress-PTSD model," he says.

Prof. Bar Haim is now conducting a study involving Israeli soldiers that investigates the potential use of computer-based tasks to modify and retrain the attention system of the afflicted patient. Called "Attention Bias Modification Treatment," the approach has been successfully applied in several clinical trials both in the U.S. and in Israel. Soon it will be tested in IDF veterans with PTSD.

Prof. Bar Haim emphasizes that the treatment of anxiety-related disorders is not an easy task. But he hopes that his work in the field, coupled with imaging technologies and computer software, will lead to more effective ways of treating victims of anxiety and PTSD so they can lead normal and healthy lives.