(PS8-D79) How Do We Target Non-suicidal Self-injury in Borderline Personality Disorder? Exploring the Relationship Between Emotion Dysregulation, Interpersonal Dysfunction, and Non-suicidal Self-injury

Dialectical Behaviour Therapy (DBT; Linehan, 1993) is recognized as an evidence-based treatment for borderline personality disorder (BPD) and is associated with improvements in several BPD-related features, most notably non-suicidal self-injury (NSSI). Theory and research posit that key mechanisms explaining reductions in NSSI may be via reductions in emotion dysregulation (e.g., Linehan, 1993; Chapman et al., 2006) and interpersonal dysfunction (e.g., Brickman et al., 2014; Choi-Kain et al., 2010). However, little research has examined the trajectory of change in NSSI, emotion dysregulation, and interpersonal dysfunction over DBT, nor the pathway through which NSSI decreases in DBT. Therefore, the current research investigated: 1) the trajectory of changes in emotion dysregulation, interpersonal dysfunction, and NSSI frequency over the course of standard DBT, and 2) whether changes in emotion dysregulation mediates the relationship between changes in interpersonal dysfunction and changes in NSSI over in treatment. 120 individuals with BPD enrolled in a multi-site randomized-clinical trial (McMain et al., 2022) were assessed at five timepoints over 12 months of standard DBT. Latent growth curve modeling of the three variables revealed that interpersonal dysfunction ((β = -5.48, SE = 0.97, p < 0.01) and NSSI (β = -0.836, SE = 0.09, p < 0.01) decreased linearly over the course of DBT, whereas emotion dysregulation decreased in a quadratic manner (β = -11.564, SE = 1.559, p < 0.01) such that most of the gains in emotion dysregulation occurred in earlier phases of DBT (β = 1.005, SE = 0.372, p < 0.01). A parallel process mediation analysis, which plots the trajectory of change for variables in relation to each other, revealed that, although changes in interpersonal dysfunction predicted changes in emotion dysregulation (β = 0.701, p < 0.01), changes in emotion dysregulation did not significantly mediate the relationship between changes in interpersonal dysfunction and in NSSI (β = 0.02, p = 0.99). The findings suggest DBT effectively reduces NSSI frequency, emotion dysregulation, and interpersonal dysfunction; however more work is required to understand the pathway through which NSSI frequency decreases in DBT.