Effects of Short‐Term Versus Long‐Term Mentalization‐Based Therapy on Psychiatric Symptoms in Outpatients With Borderline Personality Disorder: Exploratory Results From a Randomized Clinical Trial

ABSTRACT

We conducted a randomized clinical trial assessing the beneficial and harmful effects of short‐term versus long‐term mentalization‐based therapy (MBT) for outpatients with borderline personality disorder (BPD) and found no evidence of a difference on BPD symptom severity, functional impairment, quality of life, global functioning, and severe self‐harm. In this paper, we assessed the effects of short‐term versus long‐term MBT on the exploratory outcome, psychiatric symptoms, assessed with the Symptom Checklist‐90‐Revised (SCL‐90‐R). Participants included the full intention‐to‐treat sample of the original trial of N  = 166 randomized outpatients with subthreshold or a diagnosis of BPD (short‐term MBT n  = 84, long‐term MBT n  = 82), who were randomly assigned to short‐term MBT (5 months) or long‐term MBT (14 months). Psychiatric symptoms were assessed with the SCL‐90‐R at baseline, 8, 16, and 24 months after randomization. The 16‐month time point was predefined as our time point of primary interest. Regression analyses showed no evidence of a difference when assessing general symptom severity (MD −0.02, 95% CI −0.24–0.20; p  = 0.841) or any of the subscales, including anxiety, depression, hostility, interpersonal sensitivity, obsession/compulsion, paranoid ideation, phobic anxiety, psychoticism, and somatization. At the exploratory 24‐month follow‐up time point, similar results were obtained. In conclusion, short‐term MBT neither weakened nor improved patients' psychiatric symptoms compared with long‐term MBT for outpatients with BPD.

Trial Registration: ClinicalTrials.gov: NCT03677037