Re-examining the comorbidity between borderline personality disorder and post-traumatic stress disorder: a systematic narrative review

BACKGROUND: Borderline personality disorder (BPD) and post-traumatic stress disorder (PTSD) frequently co-occur, yet research on this comorbidity is limited. Recent advancements in this area have led to the emergence of new studies that provide insight into the relationship between these disorders, potential treatment interventions, and the ongoing debate surrounding the diagnosis of Complex PTSD. This review aims to examine these findings and evaluate whether they address key gaps identified in the review by Frías & Palma (Psychopathology 48(1):1–10, 2014). METHODS: A literature search was conducted using Medline and PsycINFO databases covering the period from 2014 and 2024, using the following descriptors: ‘post-traumatic stress disorder’, ‘posttraumatic stress disorder’, ‘PTSD’, ‘borderline personality disorder’, and ‘BPD’. RESULTS: A total of 27 studies met the inclusion criteria for examining this comorbidity, with the majority focusing on psychotherapy treatments. Consistent with previous findings, high comorbidity rates persist in clinical and community samples, and emotion dysregulation appears to be a core feature of BPD-PTSD. Contrary to common belief, a comorbid diagnosis of PTSD did not hinder treatment effectiveness, and individuals with a dual diagnosis showed improvements comparable to those with either disorder alone. Although some patients report increased distress or dysfunction, BPD-specific, trauma-focused, and integrated treatments are well-accepted in BPD-PTSD populations. While BPD-specific interventions are beneficial in managing BPD symptoms, evidence suggests that trauma-focused treatments are the most validated and central approaches for addressing this comorbidity. Incorporating emotion regulation techniques as strategies within or alongside trauma-focused treatments may further enhance outcomes for individuals with BPD-PTSD. CONCLUSIONS: Our review builds on evidence that this comorbidity is treatment responsive. Despite the expanding understanding of these co-occurring disorders, gaps in the literature prevail. Further research on the prevalence, course, and etiology is needed, as well as on the efficacy of psychopharmacology treatments and the underrepresentation of men in BPD-PTSD samples.