Comparison of prototypic cases of depressive personality disorder and dysthymic disorder

Although depressive personality disorder (DPD) was included in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV; American Psychiatric Association, 1994) appendix as a proposed category needing further research, there are concerns that it overlaps excessively with dysthymic disorder (DD). The purpose of this investigation was to identify the characteristic features of representative patients with DPD and patients with DD, and to determine whether they could be distinguished by their symptoms. Two matched samples of psychologists (n=57, n=48) identified a prototypic patient with DPD or DD, provided demographic and treatment information about the patient, and rated the patient's symptoms on a series of mood and personality disorder symptoms taken from the DSM-IV and the literature. When composite descriptions were constructed using the highest rated symptoms, there was considerable overlap in symptoms of identified DPD and DD patients. The DSM-IV research criteria for DPD provided the best description of the DPD patients; however, there was a high degree of correlation between DPD and DD criteria sets. There was also considerable comorbidity, with the majority of the patients in both groups meeting criteria for DPD and DD. However, there was a significant difference in comorbid diagnoses (and other differences in family history, outcome, and treatment history that failed to reach the more stringent level of statistical significance, i.e., p<.001) suggesting that there may be some important differences between DPD and DD. Nevertheless, the symptom ratings imply blurred boundaries between DPD and DD, suggesting the need for clearer differentiation between the two disorders or the need to adopt an alternative model of classification.