Abstract
BACKGROUND: To investigate differences in biological characteristics and factors associated with depressive disorder with or without nonsuicidal self-injury (NSSI) in adolescents. METHODS: This study enrolled adolescents aged 12-18 years, including patients with first-episode depression and healthy controls. According to the Diagnostic and Statistical Manual of Mental Disorders, patients were divided into an NSSI group and a non-NSSI group. Collected data included demographic variables (sex, age, years of education), psychological scale scores (Self-Rating Anxiety Scale [SAS], Self-Rating Depression Scale [SDS]), and biological indicators (folate, immunoglobulins, complement, inflammatory factors). Differences among the three groups were compared using analysis of variance, and correlates of NSSI were explored using regression analysis. RESULTS: The study included 110 patients with first-episode depression and 55 healthy controls. Among the patients, 57 were classified into the NSSI group and 53 into the non-NSSI group. The following results were obtained: (1) The three groups differed significantly in sex, SAS and SDS scores, and levels of folate, complement 3 (C3), and interleukins 6 and 4 (p < 0.05). (2) Female sex and high C3 levels were positively associated with NSSI, whereas age and high folate levels were inversely associated with NSSI. High folate levels were a protective correlate in the non-NSSI group. CONCLUSION: Demographic factors such as sex and age influence the development of depressive disorders with comorbid NSSI. In addition, levels of C3 and folate may be related to NSSI behavior in patients with depression.