Emotional and interpersonal states following dialectical behavioral therapy in adolescent borderline personality disorder: A proof-of-concept ecological momentary assessment outcome study.

Objective: The effects of Dialectical Behavioral Therapy for Adolescents (DBT-A) on emotional and interpersonal instability were explored in adolescents exhibiting Borderline Personality Disorder (BPD) features, using ecological momentary assessment (EMA) to reduce recall bias.Method: N = 28 help-seeking female adolescents were enrolled, meeting ≥ 3 DSM-IV BPD criteria. BPD criteria, non-suicidal self-injury (NSSI), and depressive symptoms were examined pre- and post-DBT-A treatment (mean duration: 42.74 weeks, SD = 7.46). Participants maintained e-diaries pre- and post-treatment, hourly rating momentary affect, attachment to mother and best friend, and self-injury urges.Results: Interview-rated BPD symptoms decreased (χ²(1) = 5.66, p = .017), alongside reduced self-rated depression severity (χ²(1) = 9.61, p = .002). EMA data showed decreased NSSI urges (χ²(1) = 9.05, p = .003) and increased mother attachment (χ²(1) = 6.03, p = .014). However, mean affect, affective instability, mean attachment to the best friend, and attachment instability showed no significant change over time.Conclusion: DBT-A yielded limited evidence for altering momentary affective states and instability in adolescents based on EMA. Nevertheless, significant effects were observed in reducing NSSI urges and enhancing interpersonal dynamics during treatment, as assessed via EMA.