Affect Intensity and Lability: The Role of Posttraumatic Stress Disorder Symptoms in Borderline Personality Disorder

Borderline personality disorder (BPD) is characterized by symptoms of severe mood disturbance, impulsive behaviors, inappropriate anger, self-harm behaviors, relationship problems, and identity disturbances [1]. One of the prevailing theories in the BPD field suggests that emotion dysregulation is the disorder’s central feature [2, 3, 4]. According to this perspective, the multitude of impulsive behaviors in which individuals with BPD engage - such as self-injury, impulsive spending, substance use, or unsafe sexual behavior - represent maladaptive attempts to modulate the intense and rapidly fluctuating affects these individuals experience. Further, emotion dysregulation may be of sufficient intensity to alter the individual’s thoughts about the self and others, resulting in both the identity disturbances as well as the interpersonal difficulties (e.g., fluctuations between idealizing and devaluing others) observed in the disorder. Aside from self-injurious behavior, emotion dysregulation has been found to be the BPD criterion most predictive of prospective suicidal behavior, and the only BPD criterion significantly predictive of suicide attempts [5]. Further, research suggests that levels of emotion dysregulation are stable over time [6] and are the best longitudinal predictor of self-reported self-harm, identity, and interpersonal problems [7]. Adding additional complexity to the understanding of the heterogeneity of BPD, and the role of emotion dysregulation in BPD, is the incidence of high rates of co-occurring Axis I diagnoses. In one sample of 59 outpatients meeting criteria for BPD, all but one met criteria for an Axis I condition and 70% met criteria for 3 or more Axis I conditions [8]. High rates of mood disorders [9, 10, 11, 12], eating disorders [13], substance use disorders [14, 15], and anxiety disorders [12, 16, 17, 18] have been documented in BPD. Among the anxiety disorders, a recent large nationally representative study examined the comorbidity of posttraumatic stress disorder (PTSD), specifically, with BPD. Thirty percent of individuals diagnosed with BPD were also diagnosed with PTSD, and 24% of individuals diagnosed with PTSD were also diagnosed with BPD [19]. Further, co-occurring BPD-PTSD was associated with poorer quality of life, increased odds of a lifetime suicide attempt, more Axis I diagnoses, and a higher prevalence of repeated childhood traumatic events. Of the Axis I conditions, PTSD is of particular interest to the study of BPD and emotion dysregulation. Exposure to traumatic events has been linked to emotion dysregulation in the absence of PTSD or BPD [20, 21], and emotion dysregulation has been related independently to PTSD. In one study, PTSD symptom severity, as well as a PTSD diagnosis, was related to greater self-reported emotion dysregulation; and similarly, emotion dysregulation was associated with greater PTSD symptom severity, above and beyond the variance accounted for by trait-level negative affectivity [22]. Recent work suggests that emotion under-modulation may be particularly relevant for reexperiencing and hyperarousal PTSD symptoms [23, 24]. Furthermore, psychobiological deficits in emotion regulation mechanisms among individuals with PTSD continue to be documented in laboratory-based psychophysiology and neuroimaging studies [21]. The purpose of the current study was to examine the relationship between PTSD and emotion dysregulation, conceptualized as negative affect intensity (strength of emotional reaction to stressful life events) and affective lability (instability of emotional states), in a sample of individuals who met diagnostic criteria for BPD and a DSM-IV Criterion A event. Given the established independent relationship between PTSD and emotion dysregulation and the more varied and complex presentation of BPD pathology by comparison, it was hypothesized that, in an all BPD sample, PTSD symptoms, but not BPD symptoms, would evidence significant positive relations to emotion dysregulation when examined simultaneously. Further, given previous research suggesting that under-modulation of affect is associated with re-experiencing and hyperarousal PTSD symptoms, it was hypothesized that these symptom clusters would be more strongly associated with the dimensions of emotion dysregulation assessed here (i.e., affective lability and negative affect intensity).