More than a decade after the 2001 attack on the World Trade Center, some New Yorkers cannot fly because they are afraid of airplanes, or they avoid all tall buildings or cannot set foot in Lower Manhattan. Their posttraumatic stress disorder (PTSD) is unremitting. Even today, rates of chronic PTSD in WTC survivors hover around 13 percent.
But results of a pilot study may help World Trade Center PTSD patients "get their lives back," says lead investigator Dr. JoAnn Difede, director of the Program for Anxiety and Traumatic Stress Studies at Weill Cornell Medical College.
The research, published Dec. 9 in the journal Neuropsychopharmacology, found that the majority of patients who received the medication D-cyclsoserine in combination with virtual reality exposure therapy (VRE) went into remission during treatment and stayed that way through the six months of the study. "These patients began to improve substantially after the third of 12 treatments," Dr. Difede says.
The study was the first to test the use of D-cycloserine (DCS) with virtual reality exposure therapy for PTSD. It took an unusual approach to PTSD treatment by using the medication to enhance the learning that occurred during the psychotherapy, rather than the traditional strategy of using medication to relieve the symptoms of PTSD, such as anxiety and difficulty sleeping. Previous studies in animals have shown that DCS enhances extinction learning - the same process that is thought to explain how exposure therapy works in PTSD patients. In essence, patients learn to "extinguish" their association of danger with a given trigger. The process is a kind of reversal of classical conditioning, in which a previously neutral cue becomes scary after it is paired with something frightening.
VRE puts patients into an immersive virtual world. Patients put on a head-mounted display that creates an illusion of a three-dimensional environment. A therapist uses a keyboard to recreate the precise stimuli that elicits fear — a fight or flight response in the patient, whether the trigger is looking at a tall building or seeing an airplane fly overhead.
By exposing patients to the fear cues in a safe environment, therapists attempt to train a patient's brain not to react with fear and anxiety to previously neutral cues, such as tall buildings and stairwells, that became associated with the traumatic event. Dr. Difede developed the virtual reality software used in the study with Hunter Hoffman of the University of Washington, and Weill Cornell researchers Drs. Judith Cukor, Megan Olden, Katzyrana Wyka, Francis Lee and Margaret Altemus collaborated on the investigation.
Over 10 weeks, study participants took a placebo or low dose of the medication 90 minutes before each exposure therapy session. While both groups showed significant improvement in their PTSD symptoms, the VRE-DCS group showed earlier, greater, and longer-lasting improvement compared to the VRE-placebo group, Dr. Difede says. "The most difficult PTSD effects to treat are anger, irritability and sleep dysfunction, and we saw a drastic improvement, early on, in all of these symptoms," she says.
DCS, known by its trade name Seromycin, was developed in 1960 as an antibiotic to treat tuberculosis, and is still used in the developing world for the infection. It was repurposed in the early 1980's as a cognitive enhancer, becoming one of the first Alzheimer's drugs. Once scientists found that DCS can reach the brain and affect the functioning of neurons, learning, and the ability of the brain to heal itself, they began studying its effectiveness against various psychiatric disorders.
Virtual reality exposure therapy for PTSD is being extensively studied and its use is gaining acceptance, Dr. Difede says. She is leading a national study, funded by $11 million from the U.S. Department of Defense, to test two forms of exposure therapy, including VRE in combination with DCS in 300 soldiers deployed to Operation Iraqi Freedom/Operation Enduring Freedom. An estimated 8 to 9 percent of the population is at risk for PTSD at least once in their lifetimes.
"While more research is needed, our results hold promise for reducing the stress and disability associated with PTSD," Dr. Difede says. "This may be especially important for those in occupations at risk, including firefighters, police officers and soldiers."