Understanding suicidality among sexual and gender minority youth: Applying the interpersonal psychological theory of suicide.

The Interpersonal Psychological Theory of Suicide (IPTS) has been widely applied in suicide research, including studies involving LGBTQ+ people. However, longitudinal tests of the theory, particularly those integrating the moderating role of acquired capability for suicide, remain limited. The present study evaluated the IPTS using a three-wave longitudinal design with data from 662 LGBTQ+ youth ages 15-21 at baseline located in two major U.S. regions. Latent structural equation modeling was used to examine whether perceived burdensomeness and thwarted belongingness at Wave 1 predicted suicidal behavior at Wave 3 indirectly through suicidal ideation at Wave 2, and whether these associations varied as a function of acquired capability for suicide. Perceived burdensomeness significantly predicted later suicidal behavior through suicidal ideation, whereas the indirect effect from thwarted belongingness was not significant. The indirect effect from perceived burdensomeness to subsequent suicidal behavior was stronger at higher levels of acquired capability for suicide. The indirect effect from thwarted belongingness was not contingent on acquired capability for suicide. These findings provide partial longitudinal support for the IPTS among LGBTQ+ youth and underscore the importance of acquired capability for suicide in understanding escalation from suicidal thoughts to action. Implications for future research are discussed.