Suicidal Behaviors in Surviving Monozygotic and Dizygotic Co-Twins: Is the Nature of the Co-Twin's Cause of Death a Factor?

Authors

  • Nancy L. Segal PhD

    Corresponding author
    1. Department of Psychology at California State University, Fullerton.
      California State University, 800 N. State College Blvd., Psychology Department, Fullerton, CA 92834; E-mail: nsegal@fullerton.edu
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  • This work was supported by intramural faculty research awards to the author from California State University, Fullerton. Dr. Alec Roy critiqued an earlier version of this manuscript. Vanessa Harris, Alyssa Vanevery, Christian von Pohle, and Chaundra Jones provided research assistance.

California State University, 800 N. State College Blvd., Psychology Department, Fullerton, CA 92834; E-mail: nsegal@fullerton.edu

Abstract

Genetically informative samples can address hereditary and experiential influences on suicide-related behaviors. The frequency of suicide-related behaviors was compared in twins from two survivor groups: (1) those whose co-twins' deaths were suicides (monozygotic [MZ]: n = 47; dizygotic [DZ]: n = 31), and (2) those whose co-twins' deaths were nonsuicides (MZ: n = 347; DZ: n = 170). The frequency of suicide attempts among suicide survivors was significantly higher in MZ than DZ twins, while the frequency of suicide attempts among nonsuicide twin survivors did not differ between MZ and DZ twins. Twin concordance for suicide attempts more likely reflects a genetic predisposition than a behavioral reaction to the loss.

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