Efficacy of Mentalization-based group therapy for adolescents: the results of a pilot randomised controlled trial

Self-harm is one of the most prominent risk factors for suicide [1, 2]. A recent Scottish study reported that one in six young people had engaged in non-suicidal self-harm whilst one in nine young people had attempted suicide [3]. 10–25% adolescents repeat self-harm behaviours within a year [2, 4]. Adolescents who self-harm are more likely to experience a wide range of psychosocial problems later in life [5]. Self-harm often occurs within the context of a wider, complex mental health presentation, involving the interaction of a variety of social, psychological and cultural factors [4], most commonly with depressive disorders, posttraumatic stress disorder, substance abuse, and borderline personality disorder (BPD) [2, 6, 7]. A majority (62.4%) of those who die by suicide aged 35 years and younger were found to have presented to health services the year preceding their death [8]. This provides significant potential for early intervention to decrease self-harm and suicide prevalence, and also to prevent the escalation of parallel emotional distress and functional impairments.

Difficulties such as emotion dysregulation and decreased social functioning are predictive of self-harm in young people [9, 10]. It has also been suggested that self-harm can be understood in the context of reduced and or a temporary loss of mentalizing capacity, particularly in the context of interpersonal stress. Mentalizing is the mental activity that enables us to perceive and interpret human behaviour in terms of intentional, motivational and emotional mental states (e.g., needs, desires, feelings, beliefs, goals, purposes, and reasons) [11, 12]. Self-harm is in part presumed to be the result of a failure to make sense of social experience, resulting in reduced adaptive coping and impulsive behaviours including self-harm [12, 13]. Indeed, mentalization was recently found to be the only independent variable to predict higher risk of suicide in psychiatric adult inpatients [14].

A number of approaches with little to no evidence are currently considered to be best-practice within clinical settings [15]. The need to further develop and replicate trials for self-harm in adolescence has been repeatedly highlighted throughout the literature [16‐19]. Two recent systematic reviews evidenced promising effects for three therapeutic interventions namely cognitive behavioural therapy, dialectal behaviour therapy (DBT), and MBT [17, 19]. MBT, which was initially developed for the treatment of adults with a diagnosis of borderline personality disorder (BPD), directly addresses the fragile mentalizing capacity that is a core feature of BPD [20] and other complex pathology. Within an adult BPD population, MBT reduced self-harm, emotional distress and inpatient stays, and improved social function in comparison to treatment as usual [21] with continued improvements at 18 months [22]. MBT was also associated with reduced self-harm in an adult outpatient setting [23].

In relation to the adolescent population, MBT-A was more effective than treatment as usual for young people who self-harm [13]. The treatment protocol involved weekly individual MBT-A sessions and monthly MBT family therapy (MBT-F) delivered over 12 months. In a non-controlled pilot, self-reported self-harm reduced in the context of an intensive MBT group programme for adolescents with BPD or subthreshold BPD that included introductory psychoeducational group sessions, 34 sessions of MBT group-therapy and 7 sessions of MBT-parents (MBT-P) [24]. Psychoeducational group sessions aim to increase understanding of mentalizing, emotion regulation and so on, whilst group therapy sessions are more process-focussed, aiming to facilitate mentalizing between group participants. It is not known which modalities of MBT (individual, group, family, parents) are most effective or instrumental in any observed clinical change. Furthermore, little is known about the required intensity of intervention.

In our own version, we adapted the introductory MBT group with adults (MBTi) [25] for use with an adolescent population (MBT-Ai). A key aim is the development of MBT knowledge about underlying principles and concepts of mentalization. Whilst MBTi for previous trials was designed as a psychoeducation precursor to a combination of MBT individual and group therapy, our MBT-Ai programme incorporates a number of experiential tasks and role plays to encourage the application of mentalization principles to common interpersonal dilemmas.

The present study aims to evaluate the feasibility and effects of 12 week MBT-Ai for the reduction of self-harm and crisis presentations in a group of young people already receiving treatment within specialist NHS Child and Adolescent Mental Health Services (CAMHS).

We report on the proportion of potential participants who consented to participate in the trial, group attendance, ability to follow-up participants, trial withdrawals, and serious adverse events. We also report on the clinical characteristics of the trial participants at entry, end of treatment and follow-up, including any group differences. Study methodology will be reported in accordance with the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) statement and guidelines [26]. Further information about the development of the group protocol and trial methodology is available elsewhere [27].

MBT-A has shown promising effects [13]. However it is not known which MBT modality (individual, group, family), or combination of modalities, is most effective, nor how long or intensive therapy needs to be order to confer benefit.

We found that a pilot RCT of group-based MBT-Ai to reduce self-harm is both feasible and acceptable to participants. Clinicians expressed significant interest in referring to the trial, perhaps reflecting a lack of viable treatment options for these young people. Our broad inclusion criteria may also have contributed to our successful recruitment strategy, facilitating easy referral from clinicians. Not surprisingly for a clinical sample, our population experienced high levels of distress and self-harm behaviour. Over half of the sample warranted further assessment of borderline personality features on the basis of their scores on a self-report measure. Nonetheless, having recruited on the basis of self-harm behaviour from all teams within CAMHS, our population was somewhat heterogeneous. Ensuring that young people understood that randomisation may result in no additional treatment seemed to mitigate against any undue attrition from the control group. During a previous pilot phase young people had expressed a strong preference for groups to have closed membership, so a major challenge was to ensure that pre-randomisation procedures occurred quickly enough to allow the groups to begin in a timely manner.

In total we ran three separate groups. MBT-Ai group attendance was adequate, although 27% of participants randomised to active treatment attended no sessions at all. This perhaps reflected either an ambivalence about seeking help for self-harm even within a cohort already receiving treatment from CAMHS, or the impulsivity of this population. However, half of those randomised to the MBT treatment arm attended more than 50% of sessions, which is comparable to the completed RCT of MBT-A [13]. We were able to follow-up 50% of our participants at 12 weeks and retain most of these (42% total) at 24 weeks. Again, this is similar to reports from other recent trials of self-harm interventions for adolescents [43].

Both self-reported self-harm and self-harm related hospital use reduced over time. There was no difference between groups but as a pilot study it was not adequately powered to detect small effects. In addition, for this pilot, we placed no restriction on TAU. We did collect service information in order to characterise routine clinical care [29]. We subsequently noted that 26% of the TAU alone group received a 7-week Distress Tolerance group intervention, based on the principles of DBT. DBT for adolescents who self-harm showed the largest effect sizes in a recent meta-analysis [19] and there is considerable overlap between DBT and MBT. Furthermore, 19% of participants were referred from Tier IV services, whose staff had previously been trained in AMBIT [28]. TAU for some young people might therefore consist of mentalization-influenced intervention. Further consideration should be given to the control condition for any definitive trial.

However, further analysis using data from the whole sample gave promising signals that were consistent with mentalization theory. Emotion regulation, reflective function and the interaction between reflective function and pre- treatment self-harm emerged as significant predictors of a reduction in self-reported self-harm and reflective function alone predicted reduced hospital presentation for self-harm independent of randomisation. Furthermore, measures of social anxiety, emotion regulation and borderline features all also demonstrated change over time in the expected direction. Multi-level modelling further demonstrated that baseline self-harm, risk-taking and emotion regulation influenced change over time on both self-harm outcomes. Moreover, once these had been taken into account, self-reported mentalization had a bigger effect than the other variables. Additionally, multi-level modelling indicated that mentalization had an interaction effect with baseline self-harm. The emerging picture suggests that changes in mentalization may influence self-harm outcomes, warranting further investigation of the full MBT programme for this population as well as briefer mentalization-based interventions such as MBT-Ai in a fully powered definitive trial.

Another limitation is that we did not use an interview-based measure of self-harm. This was a decision informed largely by resource limitations, whilst acknowledging that different measurement methods for assessing self-harm result in widely disparate prevalence rates [18]. We did additionally assess self-harm related hospital use through examination of patient records. This ensured that we were able to collect at least one main variable for all participants who remained in the study.

We followed our adapted treatment manual which is available on request from the authors, ensuring replicability, and took steps to ensure fidelity to the manual and to principles of MBT. We report on attrition and, importantly, serious adverse events in addition to our main outcome variables relating to self-harm, providing a comprehensive account of any potential unwanted consequences of our intervention.

The other completed [13] and ongoing [44] trials of MBT-A offer far more intensive, multi-modal therapeutic programmes. A previous meta-analysis noted that those interventions with more substantial treatment ‘dosage’ were more successful [19]. On the other hand, the relative brevity of our intervention may have been a positive for many young people who may have been reluctant to participate in a year long programme. A second consideration is the degree to which an MBT intervention needs to deliver a skills based training versus a more traditionally therapeutic programme. One of our adaptations to the adult MBT manual was to include more experiential exercises and more focus on applying MBT skills in daily life, with psychoeducation remaining a significant component of our programme. It may well be that a more therapeutic focus, in group or individual format, is required, particularly for those with more entrenched difficulties. On the other hand, our skills based approach appeared well suited to our adolescent population, many of whom had complex presentations. The more efficient delivery minimises required service resources. In the UK, CAMHS are known to be under considerable pressure, stretched for resources and frequently struggling to meet demand. Comparatively brief interventions translate into feasible practice. Given that differential effect sizes seemed to indicate that interventions with strong family components worked best [19], a potential modification would be to incorporate MBT sessions for parents/caregivers. Clinically, it would seem important to ensure that the living environment of young people is primed to provide as best a ‘mentalizing culture’ as possible. How complexity and severity of presentation influences response to different formats and levels of intensity of MBT mode of delivery should be tested in future evaluations of MBT-A.

Both study procedures and the intervention itself seemed feasible and acceptable, although a future trial would benefit from a distinct control condition. Self-reported self-harm and self-harm related hospital use reduced over the course of the intervention. In line with mentalization theory, reflective function was an independent predictor of reduced self-harm related hospital use at 12 weeks. Other variables also changed over time in the expected direction. Future research should seek to inform the required format and intensity of interventions offered.