Psychiatry · Medical Literature
Dialectical Behaviour Therapy for Eating Disorders With Comorbid Borderline Personality Disorder: A Systematic Review and Clinical Implications.
Abstract
Borderline personality disorder (BPD) and eating disorders (EDs) frequently co-occur and are associated with heightened clinical severity and emotion dysregulation. This systematic review aimed to synthesize empirical evidence on the effectiveness of dialectical behaviour therapy (DBT) in improving eating disorder outcomes among individuals with comorbid BPD and EDs. A systematic literature search was conducted across Wiley, Web of Science, SpringerLink and Scopus databases in accordance with PRISMA 2020 guidelines. Studies were included if they examined DBT-based interventions in samples with comorbid BPD and EDs and reported quantitative outcomes. Eight studies met inclusion criteria. Risk of bias was assessed using Joanna Briggs Institute (JBI) checklists, and a structured narrative synthesis was performed. Across studies, DBT-based interventions were associated with reductions in eating disorder symptom severity, maladaptive eating behaviours (e.g., binge eating and purging) and self-harm. Baseline BPD symptom severity did not consistently predict poorer outcomes and, in some cases, was associated with greater early improvements. However, substantial heterogeneity in study design, sample characteristics and outcome measures was observed, and methodological quality varied across studies. DBT appears to be a clinically relevant and promising transdiagnostic intervention for individuals with comorbid BPD and EDs. Nevertheless, the current evidence base is limited by methodological constraints, highlighting the need for well-designed randomized controlled trials and mechanism-focused research. These findings have important implications for clinical practice, supporting the use of DBT as a transdiagnostic intervention in complex comorbid populations.
Clinical relevance
Is dialectical behaviour therapy (DBT) effective at reducing eating disorder symptom severity, maladaptive eating behaviours, and self-harm in individuals with comorbid borderline personality disorder (BPD) and eating disorders (EDs)? __SNAPSHOT__ {"studyDesign":"Systematic review with structured narrative synthesis (no meta-analysis); conducted in accordance with PRISMA 2020 guidelines","setting":"Not reported (multi-database search: Wiley, Web of Science, SpringerLink, Scopus); no restriction on clinical setting or country of included studies specified in the abstract","sampleSize":"8 studies met inclusion criteria; aggregate participant N across included studies not reported in abstract","population":"Individuals with a confirmed or implied comorbid diagnosis of both BPD and an eating disorder; studies required to report quantitative outcomes and use DBT-based interventions in this population","intervention":"DBT-based interventions (standard DBT or DBT-informed/adapted formats; specific modality details not disaggregated in abstract)","comparator":"Not reported; comparator conditions within included studies not described in abstract (may vary across the 8 included studies)","primaryOutcome":"Eating disorder symptom severity and maladaptive eating behaviours (e.g., binge eating, purging); self-harm was also assessed across studies","followUp":"Not reported in abstract","fundingSource":"Not reported"}
Key findings
Across the 8 included studies, DBT-based interventions were associated with reductions in eating disorder symptom severity, maladaptive eating behaviours (specifically binge eating and purging), and self-harm. Baseline BPD symptom severity did not consistently predict poorer eating disorder outcomes; in some included studies, higher baseline BPD severity was paradoxically associated with greater early improvements. No pooled effect sizes, confidence intervals, p-values, or NNT/NNH values were reported in the abstract, precluding quantitative synthesis. Because no meta-analysis was performed, all findings represent narrative aggregation rather than statistically pooled estimates. Risk of bias was assessed using Joanna Briggs Institute (JBI) checklists; specific risk-of-bias ratings for individual studies are not described in the abstract. The abstract notes 'substantial heterogeneity in study design' (abstract text cut off), suggesting considerable variation across included studies that limits direct comparability of results.
Practice implications
This systematic review provides preliminary narrative evidence that DBT-based interventions may benefit patients with the clinically complex presentation of comorbid BPD and EDs, a population historically associated with heightened severity, emotion dysregulation, self-harm risk, and poor treatment engagement. The finding that baseline BPD severity did not consistently predict worse ED outcomes — and in some cases was linked to greater early response — challenges the common clinical assumption that BPD comorbidity necessarily portends treatment failure for eating disorders. However, several important caveats apply: (1) Only an abstract was available for review; complete methods, study-level data, and full risk-of-bias assessments could not be evaluated. (2) No meta-analysis was performed, so effect sizes are not poolable and the narrative synthesis is susceptible to qualitative aggregation bias. (3) Only 8 studies met inclusion criteria, and substantial design heterogeneity is explicitly acknowledged, limiting confidence in generalisability. (4) The specific ED subtypes (e.g., anorexia nervosa, bulimia nervosa, binge eating disorder) and DBT formats (standard full-programme vs. skills-only vs. adapted) represented across included studies are not described, making it unclear which patient subgroups or intervention formats drive the observed signals. (5) Long-term durability of benefit and comparative effectiveness against other active treatments (e.g., CBT-E, FBT) are not established. Clinicians treating patients with comorbid BPD and EDs may reasonably consider DBT-based approaches, but this review does not yet provide sufficient evidence to mandate a practice change. Confirmation from larger, well-controlled trials is needed. __LIMITATIONS__ Narrative synthesis only — no meta-analysis performed, so pooled effect sizes and statistical precision are unavailable,Only 8 included studies, likely representing a small aggregate sample; individual study Ns not reported in abstract,Substantial heterogeneity in study design acknowledged in the abstract, limiting cross-study comparability,Specific ED subtypes and DBT formats are not disaggregated, obscuring which presentations benefit most,Comparator conditions across included studies are not described; it is unclear whether any included RCTs were compared to active control treatments,Follow-up duration not reported; durability of benefit cannot be assessed,Risk-of-bias ratings (JBI checklists) are referenced but not summarised in the abstract, preventing independent appraisal,No assessment of publication bias reported in abstract,Generalisability is uncertain: demographic characteristics (age, sex, cultural background) of included study participants are not described,Abstract is truncated — full conclusions and clinical recommendations cannot be fully evaluated,Funding source not reported; potential conflicts of interest cannot be assessed __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ This PRISMA 2020-compliant systematic review of 8 studies suggests that DBT-based interventions are associated with reductions in eating disorder symptom severity, binge eating, purging, and self-harm in patients with comorbid BPD and EDs, and that baseline BPD severity did not consistently worsen outcomes. However, the absence of meta-analysis, small number of included studies, substantial design heterogeneity, and truncated abstract preclude definitive conclusions or precise effect size estimation. Clinicians may cautiously incorporate DBT-based approaches into treatment planning for this high-complexity population, but practice-changing recommendations await larger, adequately controlled trials with clearly defined ED subtypes and DBT formats.