Borderline Personality Disorder symptom comorbidity within a high externalizing sample: Relationship to the internalizing-externalizing dimensional structure of psychopathology

Background: Borderline personality disorder (BPD) is highly comorbid with both internalizing and externalizing psychopathology. The current study replicates previous findings (Eaton et al. 2011) that indicate that BPD symptomatology is best conceptualized at the intersection of the distress subfactor of the internalizing dimension and the externalizing dimension of psychopathology. Methods: Confirmatory factor analysis of the covariance among continuous measures of lifetime alcohol problems, marijuana problems, other drug problems, antisocial behavior, and conduct problems, and measures of depression, trait-anxiety, neuroticism, and BPD symptoms assessed in 837 young adults. The sample was recruited to obtain a roughly normal distribution of externalizing problems ranging from no problems to individuals of high externalizing severity leading to an overrepresentation of externalizing problems in the current sample. Results: Results indicated BPD symptoms were associated with both the externalizing dimension and the distress subfactor of the internalizing dimension and lay at the intersection of the two dimensions. Interestingly, in the current study BPD had a stronger association with the externalizing dimension than was observed in previous studies. Conclusions: The results replicated earlier findings that BPD symptoms lie at the intersection of the externalizing and internalizing-distress dimensions while using different and more dimensional measures of the pathology assessed. Current findings indicate that perhaps BPD is more heavily influenced by the externalizing dimension of psychopathology within a high externalizing sample, such as those presenting for treatment for alcohol use disorder or substance use disorder