Understanding Suicide in Young Adults: Comparative Insights from Spain and Japan Through the Interpersonal Theory of Suicide

Background: (1) Cultural differences at the interpersonal level among young adults are evident; however, how the application of the interpersonal theory of suicide (ITS) varies between different populations remains to be evaluated. This exploratory study investigated the cross-cultural relevance of the ITS constructs in young adults from Spain n = 260 and Japan n = 177. (2) Methods: All participants completed self-report questionnaires assessing thwarted belongingness, perceived burdensomeness, and acquired capability for suicide. We explored whether each construct was associated with suicide risk severity in both samples and whether the strength of the effects of thwarted belongingness and perceived burdensomeness differed between groups. (3) Results: Stepwise multiple regression analyses suggested that ‘perceived burdensomeness’ may be a key predictor of suicide risk in both samples, while the joint effect of ITS variables showed no significant contribution. (4) Conclusions: These preliminary findings offer insights into the possible cultural adaptation of suicide prevention strategies for young adults from Spain and Japan, highlighting areas for future confirmatory research.