RESUMEN
OBJECTIVE: Borderline personality disorder (BPD) consists of a persistent pattern of instability in affective regulation, impulse control, interpersonal relationships, and self-image. Although certain forms of psychotherapy are effective, their effects are small to moderate. One of the strategies that have been proposed to improve interventions involves integrating the therapeutic elements of different psychotherapy modalities from a contextual behavioural perspective (ACT, DBT, and FAP). METHODS: Patients (n = 65) attending the BPD Clinic of the Instituto Nacional de Psiquiatría Ramón de la Fuente Muñíz in Mexico City who agreed to participate in the study were assigned to an ACT group (n = 22), a DBT group (n = 20), or a combined ACT + DBT + FAP therapy group (n = 23). Patients were assessed at baseline and after therapeutic trial on measures of BPD symptom severity, emotion dysregulation, experiential avoidance, attachment, control over experiences, and awareness of stimuli. RESULTS: ANOVA analyses showed no differences between the three therapeutic groups in baseline measures. Results of the MANOVA model showed significant differences in most dependent measures over time but not between therapeutic groups. CONCLUSIONS: Three modalities of brief, contextual behavioural therapy proved to be useful in decreasing BPD symptom severity and emotional dysregulation, as well as negative interpersonal attachment. These changes were related to the reduction of experiential avoidance and the acquisition of mindfulness skills in all treatment groups, which may explain why no differences between the three different intervention modalities were observed. PRACTITIONER POINTS: Brief adaptations of acceptance and commitment therapy and dialectical behavioural therapy are effective interventions for BPD patients, in combined or isolated modalities, and with or without the inclusion of functional analytic psychotherapy. The reduction of experiential avoidance and the acquisition of mindfulness skills are related with the diminution of BPD symptoms severity, including emotional dysregulation and negative interpersonal attachment.