1. U.S. Department of Veterans Affairs, War Related Illness and Injury Study Center, VA Palo Alto Heath Care System, Palo Alto, CA 94301, USA
2. Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA
3. National Center for PTSD, Veterans Affairs Palo Alto Health Care System, Menlo Park, CA 94025, USA
4. Discipline of Psychology, Murdoch University, Murdoch, WA 6150, Australia