Joumal of Abnormal Psychology 20i2, Vol. 121.No. 3, 680-691 © 2012 American Psychological Association 0021-843X/12/$12.00 DOI: 10.]037/a0028513 Understanding Heterogeneity in Borderline Personality Disorder: Differences in Affective Reactivity Explained by the Traits of Dependency and Self-Criticism Daniel C. Kopala-Sibley and David C. Zuroff McGill University Jennifer J. Russell McGill University and McGill University Health Centre, Canada D. S. Moskowitz McGill University Joel Paris McGill University and McGill University Health Centre, Canada This study examined whether the personality traits of self-criticism and dependency respectively moderated the effects of perceived inferiority and emotional insecurity on negative affect during interpersonal interactions in individuals with borderline personality disorder (BPD). A sample of 38 patients with BPD and matched community comparison participants completed event-contingent record forms after each signifieant interaetion for a 20-day period. Multilevel models showed that, controlling for baseline levels of depressive symptoms and neuroticism, as well as lagged negative affect, event-level elevations in perceived inferiority and emotional insecurity were related to more negative affect in both groups. Event-level perceived inferiority was more strongly associated with negative affect in patients with BPD who reported higher levels of self-criticism, while event-level perceived emotional insecurity was more strongly associated with negative affect in patients with BPD who reported higher levels of dependency. No significant interactions emerged for the comparison group. These findings further our understanding of differences among patients with BPD and support the application of personality- vulnerability or diathesis-stress models in predicting negative affect in BPD. Results have implications for the design of therapies for patients with BPD. Keywords: borderline personality disorder, self-criticism, dependency, negative affect, personality- vulnerability, affective reactivity Borderline personality disorder (BPD) is a pervasive, disabling, and difficult to treat psychiatric disorder characterized by affective insta- bility, impulsivity, and unstable interpersonal relationships (American Psychiatric Association, 2000). Some factor analytic work has sup- ported this three-factor structure (Skodol et al., 2002), with a sizable body of literature focusing on the nature of affective instability in BPD (e.g., Henry et al., 2(X)1 ; Koenigsberg et al., 2002; Nica & Links, 2009; Russell, Moskowitz, Zuroff, Sookman, & Paris, 2007), as weU as the effects of unstable relationships or interpersonal interactions on affective instability (Russell et al., 2007; Sadikaj, Russell, Moskowitz, & Paris, 2010; Stepp et al., 2011). However, despite general agree- ment about these core features of BPD (Leichsenring, Leibing, Kruse, New, & Leweke, 2011), there is considerable heterogeneity among patients with BPD, such as those who are relatively more or less concerned about interpersonal rejection and emotional This article was published Online First June 11, 2012. Daniel C. Kopala-Sibley, David C. Zuroff, and D. S. Moskowitz, De- partment of Psychology, McGill University; Jennifer J. Russell and Joel Pads, Department of Psychiatry, McGill University and McGill University Health Centre, Montreal, Quebec, Canada. Correspondence concerning this article should be addressed to Daniel C. Kopala-Sibley, Department of Psychology, McGill University, 1205 Dr. Penfield Avenue, Montreal, Quebec, H3A lBI Canada. E-mail: daniel.kopala-sibleyCs'mail.mcgill.ca security (Bomstein et al., 2010) or those who are more or less preoccupied with issues of failure and inferiority (Gunderson, 2007; Stiglmayr et al., 2005). Consistent with this research, some authors have argued that certain phenotypes or underlying person- ality structures within patients with BPD may act as diatheses that render them particularly vulnerable to the effects of Stressors that are congruent with the underlying personality factor (Gunderson, 2007). Despite this, little research has attempted to identify per- sonality factors that may elucidate the apparent heterogeneity of patients with BPD, even though a large body of evidence from other fields has shown that some personality factors are prospec- tively associated with higher levels of negative affect (Kopala- Sibley & Santor, 2009) and may confer vulnerability to increased negative affect following Stressors or negative events that threaten a person's sense of self-worth or security in relationships (e.g., Blatt, 2004; Kopala-Sibley & Zuroff, 2010; Zuroff & Mongrain, 1987). Understanding heterogeneity in BPD may be important for improving prediction of self-destructive symptoms, prognosis in treatment (see Leichsenring et al., 2011), and effectiveness of specific treatment approaches working with some patients with BPD. Accordingly, the purpose of the present study was to better understand this heterogeneity by examining the infiuence of two personality factors that may moderate the association of cognitions refiecting perceived emotional insecurity or perceived inferiority on negative affect during interpersonal interactions. 680