Interoceptive deficits, non-suicidal self-injury, and suicide risk: a multi-sample study of indirect effects.

Background. Interoceptive deficits (ID) have been associated with non-suicidal self-injury (NSSI) and suicidal behavior in multiple studies. Many of these studies are limited in scope, and have not fully examined possible mechanisms explaining how ID affect suicidal behavior. Methods. This study assesses how self-reported ID relate to suicide ideation and attempts in six distinct and geographically diverse samples of adults (n = 2706) and one sample of adolescents (n = 436). Participants responded to a variety of self-report questionnaires and interviews. Results. Contrary to our hypothesis, self-reported ID were only associated with suicidal ideation in two samples, one of which was the adolescent sample. Largely consistent with our predictions, self-reported ID exhibited an indirect effect on suicide attempts through versatility of NSSI in four of the five adult samples tested. Finally, the indirect effects of self-reported ID on suicide attempts through NSSI versatility did not act indirectly through behaviorally assessed pain tolerance. Conclusions. We found that, in adults, self-reported ID are not associated with suicidal ideation, but are connected with a history of suicide attempts, through an indirect effect via NSSI. Our findings also indicate that the mechanism of action leading from self-reported ID to suicidal behavior may differ between adolescents and adults, and relate to suicidal behavior independent of pain tolerance. Clinical implications and future directions are discussed.