Social Support and Depression Mediate the Relationship Between Childhood Trauma and Nonsuicidal Self-Injury

Nonsuicidal self-injury (NSSI), which involves the deliberate destruction of body tissue without suicidal intent, is strongly associated with an increased risk of later suicidal behaviour. Disclosing the risk factors for NSSI is therefore vital to prevent the progression to suicide. While documented evidence links NSSI to childhood trauma, depression, social support, a comprehensive perspective that integrates these factors together is lacking. To bridge this gap, we leveraged a chain-mediating model in this study, to examine the mediating effect of social support and depression on the relationship between childhood trauma and NSSI. As expected, NSSI behaviours were positively correlated with depression scores (r = 0.492, p_adj < 0.001), childhood trauma scores (r = 0.306, p_adj < 0.001), and negatively correlated with the social support scores (r = −0.168, p_adj = 0.020). Importantly, in the chain-mediating model, increased childhood trauma was associated with decreased social support (β = −0.532, t = −9.086, p < 0.001), which in turn was linked with increased depressive symptoms (β = −0.193, t = −2.957, p < 0.01), ultimately contributing to greater odds of NSSI behaviours. Our findings elucidated the complex psychological mechanisms underlying the interplay between childhood trauma, social support and depression severity, suggesting that improving social support and intervening early in depression may be potential ways to reduce the risk of NSSI.