Pilot Study Examining the Impact of a Cognitive Processing Therapy (CPT) Group for Patients With Co-Occurring Borderline Personality Disorder and Posttraumatic Stress Disorder

Borderline personality disorder (BPD) is a severe psychological disorder characterized by instability in emotion regulation, interpersonal relationships, and self-image, coupled with marked impulsivity. Additionally, individuals with BPD often meet criteria for other disorders. One of the most commonly co-occurring disorders among individuals diagnosed with BPD is posttraumatic stress disorder (PTSD). Within this population, 56% to 58% of inpatients, and between 36% to 50% of outpatients are diagnosed with co-occurring PTSD.

The high prevalence of this co-occurrence is consistent with studies documenting the severe traumatic experiences (including, but not limited to, physical, sexual, and emotional abuse, both as children and adults) commonly experienced by individuals diagnosed with BPD . Additionally, risk factors for PTSD identified by meta-analyses share striking commonalities with those of BPD, including: lack of social support, prior history of trauma (including childhood abuse), and poor psychological adjustment prior to trauma.

The co-occurrence of BPD/PTSD is associated with poorer outcomes and significant distress than the presence of either disorder alone. For example, individuals with co-occurring BPD/PTSD exhibit a lower likelihood of remission from BPD after 10 years of follow-up, and are also more likely to engage in non-suicidal self-injurious behavior (NSSI). In addition, BPD patients diagnosed with PTSD are also faced with greater emotional dysfunction and global psychological distress, as well as inferior physical health compared to individuals with BPD alone.

Several studies have proposed theories on the high co-occurrence of these disorders, but few have investigated potential treatments to address the unique issues associated with this comorbidity. The current standard of treatment for BPD, Dialectical Behaviour Therapy (DBT), has a solid empirical basis, including numerous randomized control trials (RCTs) demonstrating its efficacy in the reduction of associated symptoms. Despite the efficacy of DBT, the DBT treatment manual (Linehan, 1993) did not outline a specific protocol for intervention in patients with co-occurring BPD and PTSD. Moreover, outcomes from DBT trials indicate that DBT alone does not adequately treat co-occurring BPD/PTSD. Specifically, data from an RCT evaluating DBT in suicidal women with BPD demonstrated that only 13% of patients diagnosed with BPD/PTSD achieved full remission from PTSD during one year of DBT.

Recently, researchers have focused on identifying how to treat individuals with BPD and PTSD within the context of DBT. Harned and colleagues have developed and tested a combined DBT PE protocol that has shown efficacy in treating BPD/PTSD. This combined treatment addresses some of the problems inherent in the direct application of the conventional PTSD treatment, prolonged exposure (PE) therapy for individuals with BPD. Evaluations of PE show that PE significantly reduces PTSD symptoms and secondary outcomes such as depression. PE is designed to counteract avoidance of traumatic memories through repeated exposure to the traumatic memory, as well as in vivo exposure to non-dangerous events perceived to be fearful by the patient. The intention of the treatment is to alleviate overestimation of the likelihood and severity of negative outcomes, as well as conditioned fear responses to certain situations, often experienced by PTSD patients.