Psychobiological Mechanisms of Resilience to Trauma

This study will evaluate brain changes and psychological characteristics of people who are resilient to trauma. It will examine and compare responses in three categories of subjects: 1) people who have been exposed to a significant traumatic event and suffer symptoms of post-traumatic stress disorder (PTSD) severe enough to interfere with their ability to function; 2) people who have been exposed to a significant traumatic event and do not suffer PTSD symptoms severe enough to interfere with their ability to function; and 3) people who have never been exposed to a significant traumatic event. Most people who are exposed to trauma recover well from the adversity. Some may even benefit from it by, for example, gaining greater self-confidence of strengthening personal relationships. Others, however, develop PTSD and may have repeated thoughts, images, and dreams of the trauma; feel upset when reminded of the traumatic event; avoid places or people that remind them of the trauma; feel detached from others; have difficulty sleeping and concentrating; or startle easily. People in the three categories listed above may be eligible for this study. Candidates will be screened with a medical and psychiatric interview, evaluation of emotional intelligence (sensitivity to feelings of others), physical examination, electrocardiogram (EKG) and blood tests. Participants will undergo the following additional tests and procedures: * 24-hour urine collection and three urine drug screens over the course of the study. * Saliva collection every 2 hours on the day of the urine collection. * Magnetic resonance imaging (MRI) scans of the brain: Subjects will have three MRI scanning sessions to show brain structure and changes in blood flow in different regions of the brain that are responsible for emotion. MRI uses a strong magnetic field and radio waves to produce images of body tissues. During the scan, the subject lies on a table in a narrow cylinder containing a magnetic field and ma