Effect of family functioning on self-injury in adolescents: a test of longitudinal moderated-mediation

The rising prevalence of self-injury among adolescents urges us to explore the risk factor underlying its etiology. While previous research has highlighted the important influence of family factors on self-injury, the mechanisms behind it warrant further exploration. This study constructs three moderated mediation models to explored the longitudinal relationship between family functioning and self-injury, and examined the mediating role of depression and the moderating role of negative cognitive emotion regulation (NCER). Data were collected from 705 middle school students (345 boys and 360 girls; Mage = 13.23 years, SD = 0.87) in Hunan Province, China, through a two-wave quantitative survey conducted six months apart. The participants completed self-report questionnaires on family APGAR index scale, children’s depression inventory, cognitive emotion regulation questionnaire, and adolescent self-injury scale. The results indicate that family functioning significantly predicts adolescent self-injury later on (β = -0.095, p < 0.01). Depression at both Time 1 (T1) and Time2(T2) fully mediates the relationship between family functioning (T1) and self-injury (T2). Regarding moderation effects, NCER (T1) did not moderate the impact of depression (T1) on self-injury(T2) (β = 0.025, p = 0.43). However, NCER (T2) significantly moderated the effect of depression (T1) on self-injury (T2) (β = 0.082, p < 0.01). and also moderated the relationship between depression (T2) and self-injury (T2) (β = 0.127, p < 0.001). These findings support the experiential avoidance model and extend the existing literature by demonstrating that depression played a completely mediating role between family functioning and self-injury, which is not only immediate, but also delayed. Additionally, higher NCER as a risk factor amplified the negative effect of depression on self-injury. It implied that interventions focused on reducing depression and enhancing cognitive emotion regulation may effectively reduce self-injury.