 Overall, this study aims 1 to determine if subjects administered DCS show a significantly larger decrease in symptoms of PTSD as compared to those administered a placebo, 2 to determine if subjects administered DCS show a decrease in PTSD symptomatology significantly earlier as measured by weeks than those administered a placebo, 3 to determine if differences in symptomatology are evident at a 6-month follow-up and indicate long-term differences between groups, 4 to determine if the BDNF SNP predicts treatment response, 5to determine if it is feasible and acceptable to provide imaginal exposure IE therapy for PTSD using videoconferencing technology. 