From The Quarterly, Summer 2010
Post-traumatic stress disorder (PTSD) affects upwards of 25 percent of returning U.S. combat troops. Both men and women in the combat zone, troops and civilians alike, are exposed to the unpredictable traumas of war. The experience of the contemporary American armed forces in Iraq has also highlighted the special trauma dangers faced by female soldiers who are the victims of sexual assault. At the same time, the debilitating symptoms of PTSD are experienced by a still higher percentage of inner-city residents, who are exposed to a disproportionate rate of violence in their communities — another source of acute concern.
NARSAD Scientific Council member Dr. Kerry Ressler, a three-time NARSAD Young Investigator and winner of NARSAD’s 2009 Freedman Award, takes an interdisciplinary approach to understanding, and treating PTSD. He is combining basic studies of neurobiology and genetics with insights from psychotherapy and pharmacology to try to help defuse and possibly even prevent the formation of the terrifying and indelible memories that characterize PTSD.
A key question Dr. Ressler is exploring is why some people are more at ri sk for PTSD than others. One difference, he says, is pre-existing sensitivity. About 40 percent of the risk is genetic. Dr. Ressler has been examining a variant form of a gene that may play a key role. But genetic predisposition by itself does not predict illness. Environment is equally crucial. A large body of research has shown that childhood trauma is the strongest predictor of risk for PTSD in adulthood, an observation dramatically confirmed by Dr. Ressler and his team in interviews with 3,000 inner-city residents of Atlanta.
Studies in animal models point to a critical period in the development of the young brain when genetics and traumatic experience interact to create abnormal sensitivity to a hormone called cortisol that is released in response to stress. This sensitivity, in turn, leads to higher risk for an exaggerated fear reaction to trauma, the wellknown “fight-or-flight” response. Antidepressants like Prozac currently used to treat PTSD are inadequate. Psychotherapy techniques work to erase traumatic memories through repetition and desensitizing. Currently, researchers are testing the effectiveness of using experimental drugs that target the cortisol system in combination with psychotherapy.
It is Dr. Ressler’s hope that the findings coming out of his laboratory and elsewhere will spur the development of tools that can alleviate PTSD symptoms after they form, and perhaps also specific antagonist drugs that might be administered at the time of trauma to prevent the formation of traumatic memories.