Multimodal examination of emotion regulation difficulties as a function of co-occurring avoidant personality disorder among women with borderline personality disorder.

Despite a robust association between borderline personality disorder (BPD) and emotion dysregulation, evidence of within-BPD group differences in emotion regulation (ER) difficulties highlights the need to examine factors that increase the risk for ER difficulties within BPD. One factor that warrants consideration is co-occurring avoidant personality disorder (AVPD), the presence of which is associated with worse outcomes in and outside of BPD and theorized to interfere with adaptive ER. Thus, this study examined if co-occurring AVPD among women with BPD is associated with heightened ER difficulties (assessed across self-report, behavioral, and physiological domains). Participants included 39 women with BPD (13 with co-occurring AVPD) and 18 women without BPD. Although results revealed no significant differences in overall self-reported ER difficulties (or the specific dimensions involving emotional clarity and the control of behaviors when distressed) between BPD participants with and without AVPD (with both groups reporting greater ER difficulties than non-BPD participants), other ER difficulties were found to be heightened among BPD participants with AVPD. Specifically, BPD participants with (vs. without) AVPD reported greater difficulties accessing effective ER strategies, evidenced less willingness to experience distress on a laboratory stressor, and exhibited a greater decrease in high frequency heart rate variability in response to this stressor (indicative of poor ER capacity). Findings add to the literature on ER difficulties in BPD, suggesting that co-occurring AVPD within BPD may be associated with a lower capacity for regulating distress and greater difficulties accessing effective ER strategies, potentially leading to greater efforts to avoid emotional distress.