Sexual orientation and suicidality - A co-twin control study in adult men

Background: Several recent studies have found a higher lifetime prevalence of suicide attempts in homosexual males compared with heterosexual control subjects or population rates. These studies used either convenience samples , most without controls, or population-based samples in which confounding f actors such as depression and substance abuse were not measured. Methods: This study used twins from the population-based Vietnam Era Twin R egistry, Hines, ill. An analytic sample of 103 middle-aged male-male twin p airs from the registry was identified in which one member of the pair repor ted male sex partners after age 18 years while the other did not. Four life time symptoms of suicidality as measured by the Diagnostic interview Schedu le were analyzed: thoughts about death, wanting to die, thoughts about comm itting suicide, and attempted suicide. A composite measure of reporting at least one suicidality symptom was also assessed. Results: Same-gender sexual orientation is significantly associated with ea ch of the suicidality measures. Unadjusted matched-pair odds ratios follow: 2.4 (95% confidence interval [CI], 1.2 - 4.6) for thoughts about death; 4. 4 (95% CI, 1.7 - 11.6) for wanted to die; 4.1 (95% CI, 2.1 - 8.2) for suici dal ideation; 6.5 (95% CI, 1.5 - 28.8) for attempted suicide; and 5.1 (95% CI, 2.4 - 10.9) for any of the suicidal symptoms. After adjustment for subs tance abuse and depressive symptoms (other than suicidality), all of the su icidality measures remain significantly associated with same-gender sexual orientation except for wanting to die (odds ratio, 2.5 [95% CI, 0.7 - 8.8]) . Conclusions: The substantially increased lifetime risk of suicidal behavior s in homosexual men is unlikely to be due solely to substance abuse or othe r psychiatric comorbidity. While the underlying causes of the suicidal beha viors remain unclear, future research needs to address the inadequacies in the measurement of both sexual orientation and suicidality in population-ba sed samples.