Borderline personality traits and emotion processing : an event-related potentials study

Linehan's (1993) biosocial model of Borderline Personality Disorder (BPD) proposes that the core behaviours of BPD (e.g., interpersonal difficulties, self-harm, and impulsivity) are due to the BPD patient being unable to regulate their emotions to suit their environment. BPD patients are assumed to be more sensitive and accurate at responding to emotional cues than other people. Partial support for the theory has been provided (e.g., Wagner & Linehan, 1999) but there is a contradiction in the literature as some researchers have found that BPD patients are more accurate at identifying emotional cues than others (e.g., Frank & Hoffman, 1986) and others have found that they are less accurate (e.g., Arntz & Veen, 2001). This review examines the neuropsychological psychophysiological and biological evidence for the biosocial model and discusses the limitations of the existing research. Borderline Personality Disorder (BPD) is defined as a persistent pattern of volatility in interpersonal relationships, fluctuating self-image and emotions and noticeable impulsivity that is observable in a range of social contexts and apparent by early adulthood (American Psychiatric Association; APA, 2000). BPD is characterised by an unstable self-image, persistent feelings of emptiness, desperate efforts to avoid real or imagined abandonment, inappropriate anger or difficulties controlling anger, suicidal behaviour or threats and self-harm behaviour (Skodol et al., 2002). In addition, it is identified by paranoia or dissociative symptoms, affective instability, impulsivity in at least two areas that are destructive (e.g., binge eating, substance abuse), and unstable and passionate interpersonal relationships marked by alternating between extremes of idealisation and devaluation (Terbartz van Elst et al., 2001). Although BPD is relatively common, affecting about two percent of the general population (Clarkin, Levy, Lenzenweger, & Kernberg, 2004), little is known about the aetiology of this disorder and it is notoriously difficult to treat (Sansone & Levitt, 2005). Linehan's (1993) biosocial theory of BPD proposes that the key diagnostic features of BPD (e.g., interpersonal problems, impulsivity, and self-harm) are the result of the BPD patient being overly sensitive to emotional information in their environment and thus respond to unemotional information as though it is emotional in nature, or respond with an extreme emotional reaction to only mildly emotional cues. Very little is known about the exact nature and components of emotional processing in BPD patients. This review examines the neuropsychological, psychophysiological and biological evidence for Linehan's (1993) biosocial theory of BPD. Beginning with a summary of the clinical features, prevalence rates and demographical information pertinent to BPD, the review then examines the literature regarding genetic influences on the development of BPD and emotional processing in general. This is followed by a summary of theories of BPD, empirical studies of emotional processing in general, and empirical evidence for a difficulty in emotional processing in BPD patients. The review concludes by summarising the key results and limitations of research in this area and offering some suggestions for future research.