How often are two or more of the cluster B personality disorders diagnosed concurrently?
A patient with one cluster B disorder often seems to have numerous traits of the other cluster B disorders. A. Let’s just clarify that in the DSM-IV, “Cluster B” disorders include Antisocial Personality Disorder, Borderline Personality Disorder, Histrionic Personality Disorder, and Narcissistic Personality Disorder. I refer to this as the dramatic/erratic cluster, since the pathology tends to express itself in highly emotional, impulsive, or provocative behaviors. As your question suggests–and as DSM-IV confirms (p. 656)–one or more of these cluster B personality disorders (PDs) frequently co-occur. Cluster B PDs also co-occur with PDs from cluster A and C. A useful study of this is that of Becker et al, in the Dec. 2000 issue of the American Journal of Psychiatry. These investigators examined co-occurrence (co-morbidity) of other PDs with Borderline PD in adult and adolescent inpatients. They found that among adults with Borderline PD, 26% also met criteria for Antisocial PD; 16% fo
