The mind-in-mind study: A pilot randomised controlled trial that compared modified mentalisation based treatment with...

Mentalisation-based treatment (MBT) aims to improve reflective functioning. There is a growing evidence base outlining positive clinical outcomes for the use of MBT in eating disorder patients with co-morbid borderline personality disorder (BPD). The use of MBT has not been studied for eating disorder patients without BPD. This pilot study is an exploratory randomised controlled trial in which outcomes from MBT are compared with standard clinical management in a cohort of patients diagnosed with an eating disorder but not BPD. The main objectives were two-fold-to explore the use of MBT as a therapeutic modality and to test the acceptability and feasibility of the protocol design.

Thirty-two participants were randomised to receive either MBT or standard treatment during an inpatient eating disorders program. All patients enrolled in the study were diagnosed with an eating disorder but did not meet DSM-5 criteria for BPD. On admission patients were categorised as very underweight (BMI 15.0-16.4 kg/m² ), underweight (BMI 16.5-18.4 kg/m² ) or healthy weight range (BMI ≥ 18.5-24.9 kg/m² ). Upon discharge participants were further categorised as weight restored (BMI ≥ 18.5 kg/m² ) or non-weight restored (BMI < 18.5 kg/m² ). The primary outcome was the subscale score on the Reflective Functioning Questionnaire (RFQ-8). Secondary outcomes were subscale scores on the Eating Disorder Examination Questionnaire and the Depression, Anxiety and Stress Scale (DASS)-21. Participants were assessed at baseline and on discharge. Statistical significance was determined using repeated measurements analysis of variance (ANOVA).

Both groups experienced improvements in eating disorder symptoms and measures of psychological well-being. Participants within the MBT group exhibited greater improvements in reflective capacity as defined by the RFQ-8 however these benefits appeared to be limited to patients who achieved weight restoration at discharge. The eligibility criteria-which excluded comorbid BPD-led to challenges in recruitment which limited the power of the study analysis. As participants with a range of different eating disorder diagnoses were included this led to complexities in estimating the treatment effect within a defined cohort.

Although the small sample size must be noted as a limitation-the finding that weight restoration appears to be associated with improvements in reflective capacity in MBT would be worth exploring in a subsequent larger study. Modification of eligibility criteria and recruitment from a defined cohort may increase the efficiency of a future study.