Non-suicidal Self-injury and Depressive Symptoms: Identifying Transdiagnostic Mechanisms among Swedish Adolescents

Abstract: Non-suicidal self-injury and depressive symptoms both increase during adolescence. Although conditions for co-occurrence have been studied, no research has examined clinical levels concurrent with comorbidity during adolescence. Using data from a Swedish cohort-sequential project, sampling adolescents in 17 different public schools in three Swedish municipalities, clinically relevant cutoffs for self-injury and depression respectively were applied, creating four groups: low self-injury and depression, self-injury only, depression only and co-morbid self-injury and depression. To examine what is related to co-morbid self-injury and depression, we conducted multinomial logistic regression, testing for group differences in interpersonal experiences and intrapersonal conditions that theoretically contribute to both self-injury and depression. The results showed that gender and self-esteem were significant unique predictors of final groupings. Specifically, there were more girls reporting co-morbid symptoms than boys; and more boys than girls in the group with low (sub-clinical) levels of both. The co-morbid group also reported lower self-esteem than all other groups. Other issues contributed to the overall model, but did not reveal differences between groups. The findings suggest that self-esteem could be a transdiagnostic condition for co-morbid self-injury and depression and future research could benefit from developing a framework that addresses this.