Mentalisation-based treatment (MBT) in borderline personality disorder (BPD) has a growing evidence base, but there is a lack of effectiveness and moderator studies. The present study examined the effectiveness of MBT in a naturalistic setting and explored psychiatric and psychological moderators of outcome.
Borderline and general psychiatric symptoms, suicidality, self-harm, alexithymia and self-image were measured in a group of BPD patients (n = 75) receiving MBT; assessments were made at baseline, and subsequently after 6, 12 and 18 months (when treatment ended). Borderline symptoms were the primary outcome variable.
Borderline symptoms improved significantly (d = 0.79, p < .001), as did general psychiatric symptoms, suicidality, self-harm, self-rated alexithymia and self-image. BPD severity or psychological moderators had no effect on outcome. Younger patients improved more on self-harm, although this could be explained by the fact that older patients had considerably lower baseline self-harm.
MBT seems to be an effective treatment in a naturalistic setting for BPD patients. This study is one of the first studies of MBT showing that outcomes related to mentalisation, self-image and self-rated alexithymia improved. Initial symptom severity did not influence results indicating that MBT treatment is well adapted to patients with severe BPD symptoms.
The study was retrospectively registered 25 September 2017 in the ClinicalTrials.gov PRS registry, no. NCT03295838.