Background
Self-injurious behavior (SIB) in adolescents is a pressing public health issue, compounded by emotional dysregulation, behavioral challenges, and increased suicide risk. While much research has focused on interpersonal trauma, the impact of non-interpersonal traumatic events-such as those stemming from the COVID-19 pandemic-remains less clear.

Methods
We investigated the associations between SIB, mental health difficulties, and COVID-19-related traumatic stress in a non-clinical sample of 5,612 Greek adolescents (55.4% female; mean age = 13.42 +/- 0.96 years) from the Global Child and Adolescent Mental Health Study. Participants completed the Strengths and Difficulties Questionnaire (SDQ) to assess emotional symptoms, conduct problems, hyperactivity, and peer difficulties, and the Children's Revised Impact of Event Scale-8 (CRIES-8) to evaluate post-traumatic stress symptoms. SIB was assessed via self-report, and specific COVID-19-related experiences (e.g., quarantine, hospitalization) were recorded alongside measures of suicidal ideation and suicide attempts.

Results
Overall, 25.5% (n = 1,424) of adolescents reported engaging in SIB, 28.1% (n = 1,566) endorsed suicidal ideation, and 8.4% (n = 471) had attempted suicide. Adolescents reporting SIB had significantly higher total SDQ scores (M = 17.47 [SD = 5.82]) than those without (M = 11.22 [SD = 5.40]; p < 0.001). In logistic regression analyses, each one-point increase in emotional symptoms (OR = 1.17, 95% CI [1.12, 1.21]), conduct problems (OR = 1.17, 95% CI [1.12, 1.23]), and peer problems (OR = 1.08, 95% CI [1.03, 1.15]), as well as each one-point decrease in prosocial behavior (OR = 0.92, 95% CI [0.88, 0.96]), significantly elevated the odds of SIB. Moreover, higher intrusive symptoms on the CRIES-8 were modestly associated with increased odds of SIB (OR = 1.03, 95% CI [1.01, 1.05]). Among COVID-19-related experiences, personal hospitalization due to COVID-19 predicted SIB (OR = 1.26, 95% CI [1.04, 1.53]). Additionally, female gender (OR = 2.33, 95% CI [2.04, 2.63]), suicidal ideation (OR = 4.82, 95% CI [4.09, 5.69]), and a history of suicide attempts (OR = 5.08, 95% CI [3.77, 6.83]) further compounded the risk.

Conclusions
Our findings demonstrate a multifaceted interplay between mental health difficulties and trauma-related stress in the emergence of SIB among adolescents. These data highlight the importance of early detection and targeted interventions addressing both emotional dysregulation and trauma-specific symptoms, particularly for youth with direct, severe COVID-19 experiences, to mitigate SIB and its associated risks.