When more is not always better: Exploring treatment response in PTSD and comorbid personality disorders

This dissertation explores the comorbidity of posttraumatic stress disorder (PTSD) and personality disorders (PD), particularly in the context of treatment outcomes. Traumatic experiences, especially during childhood, can have profound effects on mental health and are implicated in conditions such as PTSD and PD. PTSD is characterized by intrusive memories, emotional numbing, and heightened arousal, while PD involves enduring patterns of maladaptive behavior and cognition. These disorders are often comorbid, with the presence of PD potentially complicating the treatment of PTSD. The dissertation comprises a series of studies aimed at understanding whether combining trauma-focused therapy for PTSD with interventions specifically targeting PD can improve treatment outcomes. It was hypothesized that simultaneous treatment would result in better outcomes, including reduced PTSD and PD symptoms, improved functional ability, and enhanced quality of life. The first study examined whether adding group schema therapy (GST) to imagery rescripting (ImRs) for individuals with PTSD and cluster C personality disorders (CPD) would be more effective than ImRs alone. The second study compared eye movement desensitization and reprocessing (EMDR) with and without concurrent dialectical behavior therapy (DBT) in treating PTSD with comorbid borderline personality disorder (BPD). Contrary to expectations, the findings revealed that concurrent treatments did not outperform trauma-focused treatments alone on any of the outcomes. Large reductions in symptoms were observed in all treatment groups. In fact, EMDR dropout rates were even higher in the EMDR+DBT group compared to EMDR only, although this was not the case for ImRs+GST, compared to ImRs only. Furthermore, reductions in PD symptoms were large and similar across all groups, raising the suggestion that trauma-focused therapy may be effective in treating PD. The dissertation also investigated predictors of treatment attendance, driven by the higher-than-expected dropout rates. Five key factors were identified: higher initial PTSD severity and a stronger therapeutic alliance were associated with greater treatment attendance. Lower education level and lower levels of social support were linked to attending fewer sessions. Finally, patients receiving concurrent treatments (i.e., EMDR+DBT or ImRs+GST) attended fewer trauma-focused sessions, possibly due to the challenging nature of managing multiple therapies simultaneously. Another study explored whether pre-treatment self-reported PD symptoms could predict treatment outcomes in routine mental health care. The results indicated that PD symptoms did not predict changes in PTSD symptoms, general psychiatric symptoms, dropout rates, or treatment intensity. Instead, baseline PTSD severity was the only significant predictor, negatively impacting symptom change. This finding suggests that screening for PD symptoms to predict treatment outcomes may not be necessary, as trauma-focused PTSD treatments were effective even for those with high levels of self-reported PD symptoms. Finally, the findings are discussed in light of their strengths and limitations. The studies suggest that additional treatment for comorbid PD in the case of a primary diagnosis of PTSD is not effective, and trauma-focused therapy should be the primary treatment. More intensive psychotherapy for PD may be reserved as a second step. Future research may explore the impact of trauma-focused interventions on PD symptoms.