Psychological Medicine

Original Articles

Borderline personality disorder co-morbidity: relationship to the internalizing–externalizing structure of common mental disorders

N. R. Eatona1 c1, R. F. Kruegera1, K. M. Keyesa2, A. E. Skodola2a3, K. E. Markona4, B. F. Granta5 and D. S. Hasina2

a1 University of Minnesota, Minneapolis, MN, USA

a2 Columbia University, New York, NY, USA

a3 University of Arizona, Tucson, AZ, USA

a4 University of Iowa, Iowa City, IA, USA

a5 National Institute on Alcohol Abuse and Alcoholism, USA

Abstract

Background Borderline personality disorder (BPD) shows high levels of co-morbidity with an array of psychiatric disorders. The meaning and causes of this co-morbidity are not fully understood. Our objective was to investigate and clarify the complex co-morbidity of BPD by integrating it into the structure of common mental disorders.

Method We conducted exploratory and confirmatory factor analyses on diagnostic interview data from a representative US population-based sample of 34 653 civilian, non-institutionalized individuals aged ≥18 years. We modeled the structure of lifetime DSM-IV diagnoses of BPD and antisocial personality disorder (ASPD), major depressive disorder, dysthymic disorder, panic disorder with agoraphobia, social phobia, specific phobia, generalized anxiety disorder, post-traumatic stress disorder, alcohol dependence, nicotine dependence, marijuana dependence, and any other drug dependence.

Results In both women and men, the internalizing–externalizing structure of common mental disorders captured the co-morbidity among all disorders including BPD. Although BPD was unidimensional in terms of its symptoms, BPD as a disorder showed associations with both the distress subfactor of the internalizing dimension and the externalizing dimension.

Conclusions The complex patterns of co-morbidity observed with BPD represent connections to other disorders at the level of latent internalizing and externalizing dimensions. BPD is meaningfully connected with liabilities shared with common mental disorders, and these liability dimensions provide a beneficial focus for understanding the co-morbidity, etiology and treatment of BPD.

(Received April 16 2010)

(Revised July 16 2010)

(Accepted July 28 2010)

(Online publication September 14 2010)

Correspondence

c1 Address for correspondence: N. R. Eaton, M.A., Department of Psychology, 75 East River Road, University of Minnesota, Minneapolis, MN 55455-0344, USA. (Email: nreaton@gmail.com)

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