Behavior Genetics

, Volume 30, Issue 4, pp 303–310

Self-Reported Zygosity and the Equal-Environments Assumption for Psychiatric Disorders in the Vietnam Era Twin Registry

  • Hong Xian
  • Jeffrey F. Scherrer
  • Seth A. Eisen
  • William R. True
  • Andrew C. Heath
  • Jack Goldberg
  • Michael J. Lyons
  • Ming T. Tsuang
Article

DOI: 10.1023/A:1026549417364

Cite this article as:
Xian, H., Scherrer, J.F., Eisen, S.A. et al. Behav Genet (2000) 30: 303. doi:10.1023/A:1026549417364

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.

Equal-environments assumption twins psychiatric disorders veterans males 

Copyright information

© Plenum Publishing Corporation 2000

Authors and Affiliations

  • Hong Xian
    • 1
    • 2
  • Jeffrey F. Scherrer
    • 1
    • 3
  • Seth A. Eisen
    • 4
    • 5
    • 6
  • William R. True
    • 1
    • 3
    • 6
  • Andrew C. Heath
    • 7
    • 8
  • Jack Goldberg
    • 9
    • 10
  • Michael J. Lyons
    • 11
    • 12
    • 13
  • Ming T. Tsuang
    • 12
    • 13
    • 14
    • 15
  1. 1.Research ServiceSt. Louis Veterans Affairs Medical CenterSt. Louis
  2. 2.Division of General Medical Sciences, Department of MedicineWashington University School of MedicineSt. Louis
  3. 3.School of Public HealthSt. Louis University Health Sciences CenterSt. Louis
  4. 4.Research and Medical ServiceSt. Louis Veterans Affairs Medical CenterSt. Louis
  5. 5.Division of General Medical Sciences, Department of MedicineWashington University School of MedicineSt. Louis
  6. 6.Missouri Alcoholism Research CenterUSA
  7. 7.Missouri Alcoholism Research Center. Department of PsychiatryWashington University School of MedicineSt. Louis
  8. 8.Department of Psychology and GeneticsWashington University School of MedicineSt. Louis
  9. 9.Health Services Research and Development Service and Cooperative Studies Program Coordinating CenterDepartment of Veterans AffairsHines
  10. 10.Epidemiology Program, School of Public HealthUniversity of IllinoisChicago
  11. 11.Department of PsychologyBoston UniversityBoston
  12. 12.Department of Psychiatry at the Brockton/West Roxbury VAHarvard Medical SchoolBrockton
  13. 13.Harvard Institute of Psychiatric Epidemiology and GeneticsBoston
  14. 14.Harvard Medical School Department of Psychiatry atMassachusetts Mental Health CenterBoston
  15. 15.Department of EpidemiologyHarvard School of Public HealthBoston