Anxiety influences the addictive feature of non-suicidal self-injury behavior via somatic symptom in adolescents with major depressive disorder.

Adolescents with major depressive disorder (MDD) frequently engage in repetitive non-suicidal self-injury (NSSI), with a subset developing addictive patterns; however, the underlying mechanisms remain unclear. In this present study, 363 hospitalized adolescents with MDD and NSSI were assessed using graphical Gaussian and Bayesian networks to explore relationships among clinical symptoms, impulsivity, and the addictive feature of NSSI. The results revealed an anxiety-somatic-addictive NSSI pathway (anxiety-somatic: 1.00/0.79, edge strength/ directionality; somatic-addictive NSSI: 0.82/0.84) and identified motor impulsivity as an independent predictor (0.80/0.57). To further validate this pathway, a clinical trial was conducted in 58 adolescents with MDD and NSSI receiving accelerated intermittent theta-burst stimulation (a-iTBS) targeting the left dorsolateral prefrontal cortex. Participants were stratified into high- and low-response groups, and mediation analyses were performed. At baseline, anxiety exerted a significant indirect effect on addictive NSSI via somatic symptom in both groups (high-response: β = 0.51,95% CI = [0.15, 1.19]; low-response: β = 0.24, 95% CI = [0.07, 0.45]), indicating a fully mediated pathway. Notably, this mediation effect was no longer significant following intervention (high-response: β = -0.02, 95% CI = [-0.17, 0.19]; low-response: β = 0.09, 95% CI = [-0.05, 0.30]). However, in the low-response group, regression analyses further confirmed somatic symptom as a predictor of NSSI addictive feature (β = 0.18, 95% CI = [0.03, 0.34]). These findings suggest that anxiety drives the addictive feature of NSSI via somatic symptom in MDD adolescents with repetitive NSSI. A-iTBS is a positive intervention for addictive NSSI.