Cross-sectional and temporal association between non-suicidal self-injury and suicidal ideation in young adults

Non-suicidal self-injury (NSSI) is a strong predictor of suicidal ideation and attempts. Consistent with the interpersonal theory of suicide, preliminary evidence suggests that NSSI is associated with higher levels of perceived burdensomeness (PB) and thwarted belongingness (TB). However, no study to date has examined the cross-sectional and prospective relationships between NSSI, TB, PB, and suicidal ideation (SI). To fill this gap, this study examined the mediating role of TB and PB in the relationship between NSSI and SI at baseline and follow-up. Young adults (N=49) with and without histories of NSSI completed self-report measures of TB, PB, and SI at three time points over two months. NSSI history was associated with higher levels of PB, TB, and SI at all time points. TB and PB significantly accounted for the relationship between NSSI history and SI at baseline. However, the relationship between NSSI history and SI at follow-up was mediated by PB, not TB. Findings provide evidence for the roles of TB and PB in the relationship between NSSI and SI, and partial support for the interpersonal theory of suicide. Future research and clinical implications are discussed.