Borderline Personality Disorder Symptom Comorbidity Within a High Externalizing Sample: Relationship to the Internalizing-Externalizing Dimensional Structure of Psychopathology.

Borderline personality disorder (BPD) is highly comorbid with internalizing and externalizing psychopathology. The current study replicates findings indicating that BPD symptomatology is influenced by the distress subfactor of both the internalizing and the externalizing dimension of psychopathology. Confirmatory factor analysis of the covariance of continuous measures of externalizing pathology, internalizing pathology, and BPD symptoms was assessed in 837 young adults. The sample contained a range of externalizing severity from none to high severity, leading to an overrepresentation of externalizing problems. BPD symptoms were associated with both the externalizing dimension and the distress subfactor of the internalizing dimension. Interestingly, BPD had a stronger association with the externalizing dimension than observed in previous studies. Results replicated earlier findings using different and more dimensional measures. Findings indicated that BPD is more heavily influenced by the externalizing dimension of psychopathology within a high externalizing sample, such as those presenting for treatment of alcohol or substance use disorders.