This study examines the association of individual and familial risk factors with exposure to trauma and posttraumatic stress disorder (PTSD) in male twins (N = 6744) from the Vietnam Era Twin Registry. Independent reports of familial psychopathology from co-twins were used to avoid the potential biases of the family history method. Risk for exposure to traumatic events was increased by service in Southeast Asia, preexisting conduct disorder, preexisting substance dependence, and a family history of mood disorders whose effects appear to be partly genetic. Preexisting mood disorders in the individual were associated with decreased odds of traumatic exposure. Risk of developing PTSD following exposure was increased by an earlier age at first trauma, exposure to multiple traumas, paternal depression, less than high school education at entry into the military, service in Southeast Asia, and preexisting conduct disorder, panic disorder or generalized anxiety disorder, and major depression. Results suggest the association of familial psychopathology and PTSD may be mediated by increased risk of traumatic exposure and by preexisting psychopathology.
1 Division of Epidemiology, Mailman School of Public Health, Columbia University, PH-18-EPI, 600 West 168th Street, New York, New York 10032.
2 Department of Psychology, Boston University, Boston, Massachusetts.
3 Harvard Institute of Psychiatric Epidemiology and Genetics, Boston, Massachusetts.
4 Harvard Medical School Department of Psychiatry at Massachusetts, Mental Health Center, Boston, Massachusetts.
5 Women’s Division, National Center for Posttraumatic Stress Disorder, Boston Veterans Affairs Medical Center, Boston, Massachusetts; and Boston University School of Medicine, Boston, Massachusetts.
6 Veterans Affairs Boston Healthcare System, Brockton, Massachusetts.
7 Seattle Veterans Affairs Epidemiological Research and Information Center/Vietnam Era Twin Registry, Seattle, Washington; and University of Washington, Department of Epidemiology, Seattle, Washington.
8 St. Louis Veterans Affairs Medical Center, Research and Medical Services, St. Louis, Missouri; and Washington University, Department of Internal Medicine, Division of General Medical Sciences, St. Louis, Missouri.
9 Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts.
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This research was supported by a grant (MH11954-01) from National Institute of Mental Health to Drs. Michael Lyons and Karestan Koenen and by a grant from the Massachusetts Area Veterans Epidemiological Research Center (MAVERIC) to Drs. Jessica Wolfe and Karestan Koenen. This research was also supported by a grant (AA10586) from the National Institute on Alcohol Abuse and Alcoholism to Dr. Michael Lyons, a grant (DA04604) from the National Institute on Drug Abuse to Dr. Ming Tsuang, and the Department of Veterans Affairs Health Services Research and the Development Service and Cooperative Studies Program (Study #992).
The authors wish to thank the Department of Veterans Affairs Health Services and Development Service, Chief Research and Development Officer, John R. Feussner, M.D., Health Services Research & Development, Director, John Dmakis, M.D.; Deputy Director, Shirley Meehan, M.B.A., Ph.D.; Hines Veterans Affairs Health Services Research and Development and Cooperative Studies Program Coordinating Center, Vietnam Era Twin Registry Director, William G. Henderson, Ph.D.; Registry Coordinator, Mary Ellen Vitek; Programmer, Kenneth Bukowski; Statistical Assistant, Rita Havlicek; Vietnam Era Twin Registry Advisory Committee, Walter Nance, M.D., (Chairman); Theodore Colton, Sc.D., Ralph Paffenbarger, M.D., Walter Nance, M.D., and Myrna Weissman, Ph.D. Drs. William R. True, Irving Gottesman, and Jag Khalsa also made important contributions to the success of this study. Most importantly, the authors wish to acknowledge and thank the members of the Vietnam Era Twin Registry for their participation and cooperation. They willingly provided sensitive information and considerable time in responding to the survey. Without their contribution this research project would not have been possible.