In the study of 28 people suffering from acrophobia, which is an abnormal fear of heights, either DCS or placebo was given to study participants, followed by two virtual reality sessions that simulated standing in a rising glass elevator. Compared to subjects who took only placebo, those treated with DCS experienced a significant reduction in their fear of heights that was maintained for at least three months (the longest time tested) after concluding therapy.
The mechanisms governing the fear response, located in a region of the brain called the amygdala, function abnormally in an acrophobic's brain. DCS binds to neurotransmitter receptors in the amygdala called NMDA (N-methyl-D-aspartate) receptors. When combined with virtual reality exposure therapy, DCS facilitates fear extinction in the acrophobic's brain.
"Cognitive behavioral psychotherapy uses a process called 'fear extinction' to treat individuals with phobias, as well as more complicated problems, such as post-traumatic stress syndrome," said Dr. Davis.
"Fear extinction involves repeated exposure to a fearful memory or object, in the absence of adverse consequences. Because it was known that DCS improves NMDA synaptic transmission and we found it improved extinction in rats, we hoped to facilitate the effects of cognitive behavioral therapy by combining DCS with virtual reality therapy in humans. Our results demonstrate that this combination is effective, and that these effects can be long lasting."
In addition to the Emory researchers, the study's authors include Libby Tannenbaum, Page Anderson, Ken Graap and Elana Zimand, all of Virtually Better, Inc., a Decatur, Ga.-based psychology clinic, and Larry Hodges of the University of North Carolina at Charlotte.
The Center for Behavioral Neuroscience (CBN), a National Science Foundation Science and Technology Center consisting of more than 90 neuroscientists at eight metro Atlanta colleges and universities, conducts research on the basic neurobiology of complex social behaviors.
The study was supported by the National Science Foundation and the National Institute of Mental Health. Drs. Rothbaum and Hodges receive research funding and are entitled to sales royalty from Virtually Better Inc., Decatur, Ga. Dr. Davis and Ressler have submitted a patent for the use of D-cycloserine for the specific enhancement of learning during psychotherapy. The terms of these arrangements have been reviewed and approved by Emory University and the Georgia Institute of Technology in accordance with their conflict of interest policies.