@article{447922a272944d089f50fc803e11b320,
title = "Self-reported zygosity and the equal-environments assumption for psychiatric disorders in the Vietnam Era Twin Registry",
abstract = "The equal-environments assumption (EEA) in twin studies of psychiatric disorders assumes that the family environment which contributes to risk for a disorder is equally correlated between monozygotic (MZ) and dizygotic (DZ) twin pairs. In a study of psychiatric disorders in female twins, Kendler and colleagues (1993) have demonstrated the utility of a test of the EEA which includes a specified family environmental factor defined by using measures of perceived zygosity. We tested the EEA assumption among 3155 male-male twin pair members of the Vietnam Era Twin Registry for the following DSM-III-R lifetime disorders: alcohol dependence, marijuana dependence, any illicit drug dependence, nicotine dependence, major depression, and posttraumatic stress disorder. The majority of MZ (81.6%; n = 1593) and DZ (90.2%; n = 1086) twin pairs agreed with the investigator's assigned zygosity. The best-fitting model for each of these disorders did not allow for a specified family environmental influence. These results support the usefulness of perceived zygosity in tests of the EEA. In male twin pairs, perceived zygosity has little impact on twin similarity for common psychiatric disorders.",
keywords = "Equal-environments assumption, Males, Psychiatric disorders, Twins, Veterans",
author = "Hong Xian and Scherrer, {Jeffrey F.} and Eisen, {Seth A.} and True, {William R.} and Heath, {Andrew C.} and Jack Goldberg and Lyons, {Michael J.} and Tsuang, {Ming T.}",
note = "Funding Information: This study was supported by the Department of Veterans Affairs Health Services Research and Development Service and the Cooperative Studies Program (Study 992). Partial support was provided by NIDA (Bethesda, MD) Grants DA4604 and DA00272; NIAAA Grants AA11822, AA10339, AA07728, and AA11998; Great Lakes Veterans Affairs Health Services Research and Development Program, Ann Arbor, MI, LIP 41-065; NIMH Grants MH-37685 and MH-31302; and NIDA Training Grant DAO72261-01 awarded to Washington University, St. Louis, MO. The authors acknowledge the work of the following people: (1) Midwest Center for Health Services and Policy Research and the Cooperative Studies Program—Vietnam Era Twin Registry, Director, W. G. Henderson, Ph.D.; Epidemiologist, J. Goldberg, Ph.D.; Registry Programmer, K. Bukowski; and Coordinator, M. E. Vitek; (2) VET Registry Advisory Committee—A. G. Bearn, M.D. (past), G. Chase, Sc.D. (past), R. R. Williams, M.D. (past), T. Colton, Sc.D., W. E. Nance, M.D., Ph.D., R. S. Paffenbarger, Jr., M.D., Dr. P. H., M. M. Weiss-man, Ph.D., and E. Cocarro, M.D.; and (3) DVA Chief Research & Development Officer—John R. Feussner, M.D.; and DVA Health Services Research & Development Service—Director, J. Demakis, M.D.; and Deputy Director, S. Meehan, M.B.A., Ph.D. The authors acknowledge Greg Carey, Ph.D., Lindon Eaves, Ph.D., D.Sc. and Irving I. Gottesman, Ph.D., for their contributions to the early development of the Twin Registry. The following organizations provided invaluable support in the conduct of this study: Department of Defense; National Personnel Records Center, National Archives and Records Administration; Internal Revenue Service; National Opinion Research Center; National Research Council, National Academy of Sciences; and Institute for Survey Research, Temple University. Most importantly, the authors gratefully acknowledge the continued cooperation and participation of the members of the Vietnam Era Twin Registry. Without their contribution, this research would not have been possible.",
year = "2000",
doi = "10.1023/A:1026549417364",
language = "English",
volume = "30",
pages = "303--310",
journal = "Behavior genetics",
issn = "0001-8244",
number = "4",
}