Trait dissociation in borderline personality disorder: influence on immediate therapy outcomes, follow-up assessments, and self-harm patterns

<b>Background:</b> Dissociative symptoms are suggested to compete with the effectiveness of psychotherapeutic treatment and frequently co-occur with early life trauma and self-harm patterns, including self-injury, suicidal ideation, and suicide attempts, which are characteristic for borderline personality disorder (BPD).<b>Objective:</b> We explore the connections between dissociation and other BPD features like self-harm and childhood traumatization and examine the impact of trait dissociation on both immediate and follow-up psychotherapy outcomes.<b>Method:</b> In this naturalistic prospective evaluation study, we investigated psychopathology including general psychological distress (SCL-90), depression (BDI-II), and borderline-specific pathology (BSL) in 131 patients with BPD pre and post of a certified 8-week inpatient Dialectical Behaviour Therapy (DBT), as well as 3- and 6-month post inpatient treatment. Prior to therapy, we evaluated trait dissociation (Dissociative Experience Scale), early life trauma (Childhood Trauma Questionnaire), and self-harm patterns (clinical interview). We performed a network analysis to explore the interplay between dissociation, self-harm, and childhood traumatization. To analyse the influence of dissociation on treatment outcomes, we employed linear mixed models.<b>Results:</b> Psychopathology (SCL-90, BDI-II and BSL) exhibited significant reductions at post-treatment and follow-up assessments when compared to baseline measurements. Higher levels of trait dissociation were consistently related to higher psychopathology but did not suggest poorer symptom reduction during DBT. However, trait dissociation predicted reduced 6-month follow-up benefits from DBT, regardless of the baseline symptom burden. The network analysis revealed a close association between self-injury and derealization/depersonalization, while the frequency of suicide attempts was more closely connected to childhood emotional abuse, which was identified as a central node of the network.<b>Conclusions:</b> Dissociation was not related to poorer outcomes regarding inpatient DBT. However, trait dissociation predicted reduced follow-up benefits, highlighting the need to address dissociation during psychotherapeutic interventions. Based on the estimated network structure, treating dissociative symptoms could potentially mitigate self-injury while especially childhood emotional abuse was linked with suicide attempts.