August 29, 2005
Clinical tool may help war verterans in dealing with PTSD
BY Poul Olson
A new clinical tool for assessing post-traumatic stress disorder (PTSD), developed by the School of Medicine, the Center for Behavioral Neuroscience (CBN) and the VA Medical Center (VAMC), could enable researchers to develop better treatments for war veterans and others suffering from the disabling anxiety disorder. Pilot studies of the system are currently being conducted with Vietnam War veterans at the Atlanta VA, and soon will be launched with Iraq War veterans at Fort Bragg, N.C., and Serbo-Croatian War veterans in Zagreb, Croatia.
PTSD, which affects an estimated 20 percent of veterans in recent conflicts, is a dysfunction of the brain’s fear-control mechanisms resulting from a psychologically traumatic experience, such as combat. One of the central features of the disorder is the inability of the brain to distinguish between safe and dangerous situations.
“The sound of a helicopter flying overhead can be enough to trigger anxiety or panic attacks in vets with PTSD; they know they are not back in combat, but they can’t suppress their fear,” said Tanja Jovanovic, an Emory and CBN postdoctoral fellow in the laboratory of Erica Duncan, assistant professor of psychiatry and behavioral sciences.
The new PTSD testing system determines the extent of brain impairment. A patient is initially conditioned to fear a series of lights by pairing their appearance with an aversive air blast to the throat. A second set of safety lights is then presented without an air blast. Finally, the two sets of lights are displayed together without an air blast to test the patient’s ability to inhibit his or her fear of the lights. Electrodes attached under the eye measure fear responses based on blink size during each of the three tests. Larger blinks indicate a greater fear reaction.
In a preliminary study of Vietnam veterans, Jovanovic and her colleagues determined PTSD sufferers were more afraid of the lights than control subjects. Veterans with more severe PTSD symptoms also could not inhibit their fear when presented with both sets of lights, indicative of the dysfunction in their fear-control mechanisms.
Clinicians typically assess PTSD sufferers based on subjective accounts of their symptoms. “This new system will provide a new way to objectively test their fear-control mechanisms,” Jovanovic said. “Our hope is that it will lead to the development of more effective treatments for PTSD and other anxiety-related disorders.”
The researchers’ next step is to determine if specific genes are involved in fear inhibition. Other studies are using functional magnetic resonance imaging to examine brain activation patterns involved.