1. National Center for PTSD; VA Boston Healthcare System; Boston MA USA
2. Department of Psychiatry; Boston University School of Medicine; Boston MA USA
3. Department of Psychiatry and School of Medicine; Virginia Institute for Psychiatric and Behavioral Genetics; Virginia Commonwealth University; Richmond VA USA
4. Seattle Epidemiologic Research and Information Center; VA Puget Sound Health Care System; Seattle WA USA
5. Department of Epidemiology; University of Washington; Seattle WA USA
6. Department of Psychiatry and Behavioral Sciences; Medical University of South Carolina; Charleston SC USA