The cohort of the current study includes 44 adult survivors of traumatic events who were assessed for post-traumatic stress within a week of the traumatic event and again 6 months later. The assessment included an MRI of the brain, psychometric testing, and structured clinical interviews. Thirty-nine (89%) of 44 consenting subjects completed the study, and 37 (95%) of those had valid MRI scans at both time points. During the traumatic event, participants in this study did not suffer a head injury or a physical injury necessitating hospital admission or major surgery. In addition, no subjects had a lifetime history of neurological disorder, psychotic disorder, PTSD, or substance abuse. The resulting PTSD and non-PTSD participants had similar mean ages (33.7 and 29.8 years, respectively), and similar mean education levels (13.4 and 12.4 years in school, respectively).