Objective Non-suicidal self-injury (NSSI) behaviors are prevalent in adolescents and have adverse effects on physical and mental health. However, little is known about the relationship between NSSI and alexithymia, or the underlying mechanisms that could explain this relationship. This study aimed to elucidate the current status of NSSI in adolescent depression, and analyze the relationship between alexithymia, loneliness, resilience, and adolescent depression with NSSI, so as to provide a theoretical basis for psychotherapeutic interventions. Method The study sample involved inpatients and outpatients from 12 hospitals across China and adolescents with depression who met the DSM-5 diagnostic criteria for depression episode. The following scales were used: The Functional Assessment of Self-Mutilation, Toronto Alexithymia Scale, UCLA Loneliness Scale, and Connor Davidson Resilience Scale. Results The detection rate of NSSI in adolescents with depression from 2021.01.01-2022.01.01 was 76.06% (1782/2343). Spearman’s correlation analysis revealed a significant correlation between alexithymia, loneliness, resilience and NSSI in depressed adolescents, and the results of the non-parametric test showed that the differences between the two groups for each factor were statistically significant. Binary logistic regression results showed that alexithymia (B = 0.023, p = 0.003, OR = 1.023, 95% CI: 1.008–1.038) and depression (B = 0.045, p < 0.001, OR = 1.046, 95% CI: 1.026–1.066) are risk factors for NSSI, resilience (B = − 0.052, p < 0.001, OR = 0.949, 95% CI: 0.935 − 0.964) is a protective factor for NSSI. Alexithymia directly predicted NSSI and also indirectly influenced NSSI through the mediated effect of resilience. Loneliness moderates the first half of the path of this mediated model. Conclusion The present study confirms a moderated mediation effect: Alexithymia can have an impact on NSSI behaviors in depressed adolescents through the mediating role of resilience. Loneliness, as a moderating variable, moderated the first half of the pathway of the mediating model. We discuss perspectives for future research and interventions based on the findings of the study.

Objective Non-suicidal self-injury (NSSI) is common among adolescents and has been linked to mental disorders and suicide in addition to physical injuries. According to the empirical avoidance model, adolescents with NSSI have stronger emotional affect and poorer emotional regulation than those without NSSI, and these constitute core features of borderline personality disorder (BPD). The relationship between borderline personality features, emotional regulation, and NSSI in the population is unclear. This study explored these associations to provide a theoretical basis for the treatment of NSSI in the future. Methods Depressed adolescents (n = 1192) were evaluated using Chinese versions of the Function Assessment of Self-mutilation Scale, Emotional Regulation Questionnaire for Children and Adolescents, and Borderline Personality Features Scale for Children. Results The majority of depressed adolescents (71.3%, 850/1192) had demonstrated NSSI in the past year, with cutting or scratching being the most common form (57.4%). Pearson correlation analysis with NSSI as a fixed factor (NSSI = 1, no NSSI = 2) revealed a negative correlation between NSSI and borderline personality features (r = -0.314, P < 0.01) but a positive correlation between NSSI and emotional regulation capacity (r = 0.159, P < 0.01), which was positively correlated with the expression suppression dimension (r = 0.079, p < 0.01); however, there was no significant correlation between the cognitive reappraisal dimension and expression suppression (r = 0.022, p > 0.05). The occurrence of NSSI was also positively correlated with borderline personality features in general (r = 0.314, p < 0.01). These results were statistically significant. Emotional regulation played a mediating role between borderline personality traits and NSSI in adolescents with depression (effect value = 0.151). Conclusion Borderline personality features and emotional regulation ability were significantly correlated with NSSI in depressed adolescents. Borderline personality symptoms not only directly influenced NSSI risk in adolescents with depression, but also indirectly influenced NSSI risk through emotional regulation.

Objective: Non-suicidal self-injury (NSSI) is common among adolescents and has been linked to mental disorders and suicide in addition to physical injuries. According to the empirical avoidance model, adolescents with NSSI have stronger emotional experience and poorer emotional regulation than those without NSSI, which are core features of borderline personality disorder (BPD). The relationship between borderline personality features, emotion regulation, and NSSI in the population is unclear. This study aims to explore these associations and provide theoretical basis for the treatment of NSSI in the future. Methods: Depressed adolescents (n = 1192) were evaluated using Chinese versions of the Function Assessment of Self-mutilation Scale, Emotional Regulation Questionnaire for Children and Adolescents, and Borderline Personality Features Scale for Children. Results: The majority of depressed adolescents (71.3%, 850/1192) had demonstrated NSSI in the past year, with cutting or scratching the most common form (57.4%). Pearson correlation analysis with NSSI as a fixed factor (NSSI=1, no NSSI=2) revealed a negative correlation between NSSI and borderline personality characteristics (r = -0.314, P < 0.01) but a positive correlation between NSSI and emotion regulation capacity (r = 0.159, P < 0.01). This results are statistically significant. Emotion regulation played a mediating role between borderline personality traits and NSSI in adolescents with depression (effect value = 0.151). Conclusion: Borderline personality features and emotional regulation ability were significantly correlated with non-suicidal NSSI in depressed adolescents. Borderline personality symptoms not only directly influence NSSI risk in adolescents with depression, but also indirectly influence NSSI risk through emotional regulation.