Am J Psychiatry 1996; 153:900-906
Copyright © 1996 by American Psychiatric Association
Understanding the comorbidity between early-onset dysthymia and cluster B personality disorders: a family study
LP Riso, DN Klein, T Ferro, KL Kasch, CM Pepper, JE Schwartz and TA Aronson
Department of Psychology, State University of New York at Stony Brook, USA.
OBJECTIVE: A number of studies have documented significant comorbidity
between dysthymia and axis II personality disorders, particularly those
grouped in cluster B. However, the nature of this comorbidity is poorly
understood. The purpose of this investigation was to use the family study
method to test five competing models of the comorbidity between early-onset
dysthymia and cluster B personality disorders. METHOD: Proband groups
consisted of subjects with early-onset dysthymia and a co-occurring cluster
B personality disorder (N = 28), subjects with early-onset dysthymia
without a cluster B personality disorder (N = 69), and a comparison group
of subjects who had never been psychiatrically ill (N = 45). The groups
were compared on rates of dysthymia with a cluster B personality disorder,
dysthymia without a cluster B personality disorder, and cluster B
personality disorders without dysthymia in their first-degree relatives (N
= 675). RESULTS: The relatives of both subgroups of dysthymic probands
exhibited higher rates of dysthymia with a cluster B personality disorder,
dysthymia without a cluster B personality disorder, and cluster B
personality disorders without dysthymia than the relatives of the never ill
probands. In addition, the relatives of probands with comorbid dysthymia
exhibited higher rates of cluster B personality disorders without dysthymia
than the relatives of probands with noncomorbid dysthymia. CONCLUSIONS:
This pattern of results is consistent with the notion that dysthymia and
cluster B personality disorders co-occur because of shared etiological
factors. This was the only one of five models of the comorbidity between
dysthymia and cluster B personality disorders that was supported by the
family data.
