Invalidating environments and adolescent non-suicidal self-injury: longitudinal cross-lagged test of negative urgency and distress tolerance.

BACKGROUND: Non-suicidal self-injury (NSSI) is a prevalent behavioural health concern during adolescence and has been consistently linked to emotionally invalidating interpersonal environments. AIMS: This study tested whether distress tolerance and negative urgency prospectively explained the link between invalidating environments and adolescent NSSI. METHOD: The study used a 2-wave longitudinal design with a 6-month interval; 300 Iranian adolescents (70% female, aged 13-17 years) participated. RESULTS: Cross-lagged panel modelling showed that invalidating environments at wave 1 predicted higher NSSI at wave 2, when we controlled for baseline NSSI, and were associated with increases in negative urgency. Although both negative urgency and distress tolerance were related to later NSSI, only negative urgency significantly mediated this relationship; distress tolerance and the hypothesised serial pathway did not show significant associations. Sensitivity analyses indicated developmental differences across age groups. CONCLUSIONS: The findings highlight impulsive response under distress as a central mechanism linking environmental invalidation to adolescent NSSI and identify negative urgency as a key intervention target.