Testing the Biosocial Theory of Borderline Personality Disorder: The Association of Temperament, Early Environment, Emotional Experience, Self-Regulation and Decision-Making
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Borderline Personality Disorder (BPD), as defined by the DSM-IV-TR (APA, 2000), is a multifaceted mental illness characterized by pervasive instability of interpersonal relationships, self-image, affect and behavior. Despite a growing consensus that the etiological basis of BPD stems from a combination of biological vulnerability and an early developmental history characterized by invalidation, abuse and/or neglect (e.g., Clarkin, Marziali, & Munroe-Blum, 1991; Linehan, 1993), the reasons for the diversity of troubling symptoms (e.g., self-injury, suicidality, mood reactivity, relationship difficulties) remain unclear. Psychopathology theorists differ in their conceptualization of the fundamental problems (e.g., impulsivity vs. identity disturbance vs. emotion dysregulation) underlying BPD and further research is needed to clarify which features are central to the maintenance of the difficulties associated with the disorder. In the current research, the some of the tenets of Linehan’s (1993) biosocial theory of BPD and the core constructs implicated in her conceptualization of the disorder were explored empirically in several samples of undergraduate university students. According to the biosocial theory, difficulties regulating emotions represent the core pathology in the disorder and contribute causally to the development and expression of all other BPD features. The emotional dysregulation is proposed to emerge from transactional interactions between individuals with biological vulnerabilities (i.e., a highly arousable temperament, sensitive to both positive and negative emotional stimuli) and specific environmental influences (i.e., a childhood environment that invalidates their emotional experience). The theory asserts that the dysregulation affects all aspects of emotional responding, resulting in (i) heightened emotional sensitivity, (ii) intense and more frequent responses to emotional stimuli, and (iii) slow return to emotional baseline. Furthermore, Linehan proposed that individuals with BPD lack clarity with respect to their emotions, have difficulties tolerating intense affect, and engage in maladaptive and inadequate emotion modulation strategies. As a result of their dysfunctional response patterns during emotionally challenging events , individuals with BPD fail to learn how to solve the problems contributing to these emotional reactions. In accordance with this theory, a number of hypotheses were tested. First, it was hypothesized that the interaction between temperamental sensitivity and an adverse childhood environment would predict BPD features over and above that predicted by either construct independently. Second, it was hypothesized that BPD traits would be predicted by high levels of emotional dysregulation (affect lability), problems across different aspects of emotional experience (e.g., intensity, awareness, clarity), and deficits in emotion regulation skills (e.g., poor distress tolerance, self-soothing). Based on the initial findings of the research, a series of competing hypotheses were tested that addressed the nature of the emotional, cognitive and motivational mechanisms that may underlie maladaptive behavior in BPD more directly. Prior to testing these hypotheses, it was important to select a set of measures that would best represent these constructs within an undergraduate population. The purpose of Studies 1a and 1b (N = 147 and N = 56, respectively) was to determine the reliability and validity of a series of self-report measures that assess BPD features and to select one questionnaire with high sensitivity (percentage of cases correctly identified) and high specificity (percentage of noncases correctly identified) as a screener for BPD within undergraduate students by comparing the results of the questionnaires against a “gold standard” criterion diagnosis of BPD (as assessed by two semi-structured interviews: DIB-R and IPDE-I). The second goal of these studies was to conduct a preliminary exploratory analysis of the association of scores on the BPD measures and constructs that have been hypothesized to be relevant to the development and maintenance of BPD symptoms (e.g., “Big Five” personality factors, emotional experience, impulsivity). Overall, the findings of Studies 1a and 1b indicated that screening for BPD in an undergraduate population is feasible and there are several questionnaires that may help in the identification of participants for future studies. Specifically, the McLean Screening Instrument for Borderline Personality Disorder (MSI-BPD; Zanarini et al., 2003), International Personality Disorder Examination DSM-IV Screening Questionnaire (IPDE-S; Loranger, 1999) and Borderline Personality Questionnaire (BPQ; Poreh et al., 2006) were all found to be internally consistent and valid screening measures. Furthermore, the results of correlation and regression analyses between dimensions of the “Big Five” and scores on the BPD measures were consistent with previous findings in the literature that BPD is associated with higher scores on neuroticism, lower scores on agreeableness, and to a lesser degree, lower scores on conscientiousness and extraversion. The similarity in results between the current and past studies suggested that individuals in the present samples showed characteristics consistent with that seen in both clinical and nonclinical populations with BPD traits. The results also provided support for the notion that individuals with BPD have a lower threshold (i.e., greater sensitivity) for both sensory and affective stimuli, as well as higher amplitude of emotional response (i.e., greater reactivity) to such stimuli. Furthermore, the findings suggested that those with BPD traits may lack understanding of their emotional state, may be unable to effectively regulate their emotional state, and that their impulsive behavior may be driven by negative affect. The purpose of Study 2 (N = 225) was to test some of the specific tenets of Linehan’s (1993) biosocial theory. The results suggested that BPD traits are associated with numerous dimensions of temperament [e.g., higher levels of negative affect; lower levels of positive affect; lower levels of effortful control; low sensory threshold (i.e., greater sensitivity) for both sensory and affective stimuli; ease of excitation (i.e., greater reactivity to sensory and affective stimuli)] and childhood environment (e.g., authoritarian parenting style, invalidating parenting, neglect, abuse). An examination of the interactions between dimensions of temperament and childhood environment suggested that interactions between (i) ease of excitation (greater reactivity to sensory and affective stimuli) and environment and (ii) trait negative affect and environment, predicted BPD symptoms over and above the temperament and environment variables alone. The results also suggested that a number of other factors are associated with BPD symptoms, including: increased attention to (or absorption in) emotional states, poor emotional clarity, affect lability (particularly anger), poor distress tolerance, and negative urgency (impulsive behavior in the context of negative affect). The association between BPD symptoms and difficulties identifying feelings seemed to be mediated by affect lability and negative urgency. Self-soothing and self-attacking did not predict BPD traits over and above the other variables. Wagner and Linehan (1999) also proposed that the intense emotions (and emotional dysregulation) experienced by those with BPD interferes with cognitive functioning and effective problem solving, resulting in poor decisions and the observed harmful behaviors. Other researchers have suggested that the repetitive, self-damaging behavior occurring in the context of BPD may reflect impairments in planning and failure to consider future consequences (e.g., van Reekum et al., 1994). Proponents of this view suggest that individuals with BPD show greater intensity and lability in their emotional response to their environment because they are unable to inhibit or moderate their emotional urges (i.e., impulsivity is at the core of the disorder). The purpose of Study 3 (N = 220) was to characterize decision making in an undergraduate sample of individuals with BPD traits and to ascertain the relative contribution of individual differences in the following areas to any deficits identified in decision making: emotional experience (e.g., increased affective reactivity or lability); reinforcement sensitivity (e.g., sensitivity to reward and/or punishment); impulsivity; executive functioning (measured by an analogue version of the Wisconsin Card Sorting Test); and reversal learning. Decision making was assessed using modified versions of two Iowa Gambling Tasks (IGT-ABCD and IGT-EFGH; Bechara, Damasio, Damasio, & Anderson, 1994; Bechara, Tranel, & Damasio, 2000) that included reversal learning components (i.e., Turnbull et al., 2006). The results of Study 3 showed that participants in the BPD group demonstrated deficits in decision-making as measured by the IGT-ABCD but not on the IGT-EFGH. The results [interpreted in the context of reinforcement sensitivity models, the somatic marker hypothesis (Damasio, 1994) and the “frequency of gain” model e.g., Chiu et al. 2008)] suggested that decision making under uncertainty may be guided by gain-loss frequency rather than long-term outcome for individuals with BPD traits. The results failed to show consistent associations between BPD symptoms and performance on either version of the IGT. Individual differences in emotional experience, executive functioning or reversal learning did not account for the decision-making problems of the BPD group on the IGT-ABCD.