Virtual Reality Therapy and Imaging in Combat Veterans With Blast Injury and Posttraumatic Stress Disorder

Inclusion Criteria 1. Over 18 years of age. 2. Able to give written informed consent prior to participation in this study. 3. Good overall health. Subjects with stable medical problems (e.g., hypertension, hypothyroidism, diabetes mellitus) that are fully under control with treatment will be included. 4. Specific criteria according to arm: 1. Healthy OIF/OEF veterans who deployed for at least 3 months in support of OIF/OEF who do not have blast exposure (i.e., within 100 feet of a blast, in which the pressure wave knocked them to the ground or caused other physical symptoms, or the vehicle in which they were riding hit an improvised explosive device, jarring them from their seat) or PTSD: PCL-M\<50, negative history of concussion or loss of consciousness. 2. OIF/OEF veterans with a history of blast exposure (as defined above) who do not meet criteria for PTSD (PCL-M \<50) 3. OIF/OEF veterans with PTSD only who receive usual care: any form of individual or group psychotherapy so long as it does not include exposure therapy, and/or may be on any combination of prescription psychotropic medications; participants in this group may or may not have a history of blast exposure, provided they did not have loss of consciousness of 60 minutes or more or otherwise meet any criteria for moderate or severe TBI. 4. OIF/OEF veterans with PTSD that will receive VRET through the WRNMMC IRB approved protocol entitled "Enhancing Exposure Therapy for PTSD: Virtual Reality and Imaginal Exposure with Cognitive Enhancer": must meet entry criteria for that study; most notably, they must have combat-related PTSD; participants in this group may or may not have a history of blast exposure, provided they did not have loss of consciousness of 60 minutes or more or otherwise meet any criteria for moderate or severe TBI. \-- Exclusion Criteria 1. Dementia or an inability to read or understand written and oral questions for any other reason. 2. The presence of a clinically significant or unstable medical disorder (e.g., unstable angina, uncontrolled diabetes mellitus, uncontrolled hypertension, symptomatic liver or kidney disease). 3. Meet DSM-IV criteria for alcohol abuse within 1 month prior to screening. 4. Meet DSM-IV criteria for alcohol and/or substance dependence within 1 month prior to screening. 5. Currently at imminent or high risk for homicide or suicide. 6. A current or past history of schizophrenia, schizoaffective disorder, and bipolar disorder. However, those with a comorbid history of other Axis 1 disorders such as major depression, dysthymia, or panic disorder will be included, if there are neither psychotic features nor significant suicidal or homicidal ideation. 7. Active pregnancy, actively seeking to become pregnant or being unwilling to use birth control measures if of child-bearing age and sexually active. 8. Residual shrapnel fragments retained within the body as a result of blast injury, or any prosthetic ferro-magnetic metal devices within the body that would pose health risks with the use of MRI. Those with MRI-safe surgical devices such as titanium will be permitted. 9. History of claustrophobia or inability to tolerate an MRI in the past without use of sedating medicine, as the use of sedating medicine could interfere with interpretation of the fMRI.