Depressive Personality Disorder: Construct, measurement, clinical correlates, and treatment outcome

Abstract: Depression is a serious and potentially devastating health problem, impacting millions of individuals worldwide. Although advances have been made in depression research, there remain a number of outstanding questions as to why certain individuals experience depression and why some respond to treatment and others do not. The present research takes a starting-point in the hypothesis that the existence of depressive personality traits (depressive personality disorder, DPD) may contribute in providing some answers to these questions. The purpose was to garner descriptive information about this type of maladaptive personality – DPD – in both non-clinical and clinical samples, and to examine DPD in terms of its clinical correlates, stability over time, and potential influence on treatment response for individuals with psychopathology in general and depression in particular. These objectives were carried out in a series of three empirical studies. Study 1 (Paper I) was designed to evaluate a translated Swedish version of the Depressive Personality Disorder Inventory, to determine its psychometric properties and suitability for use with Swedish samples. Among the 255 non-clinical volunteers who participated in the study, approximately 1 in 10 individuals qualified for DPD, and compared to those without, those with DPD reported statistically higher levels of depression, anxiety, worry, and rumination, and statistically lower levels of self-esteem, optimism, hope, and life quality. Study 2 (Paper II) took the investigation to a clinical sample of 159 clients receiving psychological services at a University clinic. A large percentage of those entering treatment - 44% - qualified for DPD, and these individuals had a comparatively more severe clinical presentation than those without DPD. The presence of DPD did not adversely affect psychotherapy outcome; rather those with DPD showed greater improvements in depression and global symptom severity as compared to those without DPD. Only 11% of the sample endorsed DPD at treatment endpoint. Study 3 (Paper III) examined a large group of psychiatric outpatients with chronic major depression (N=680), who were randomly assigned to 12 weeks of treatment with an antidepressant, nefazodone (200-600 mg/day), the Cognitive Behavioral-Analysis System of Psychotherapy (16-20 sessions), or their combination. Thirty six percent of this sample was diagnosed with DPD prior to treatment. Results indicated that DPD did not negatively impact depression outcome in any treatment modality; however, it remains unclear as to whether treatment was successful in the remediation of DPD since it was measured only at baseline. Taken together, this collection of studies convincingly demonstrates that individuals with DPD experience significant psychological distress, but they appear to respond as well or better than individuals without DPD to various types of treatment. Thus, DPD should not be viewed as an impediment to successful outcomes. Further, DPD itself appears to resolve for many individuals over the course of treatment, although future experimental work is needed to determine whether treatment is causal in the amelioration of these traits.