Stability of DSM-IV criterion symptoms for major depressive disorder.

Given the chronic and recurrent nature of major depressive disorder (MDD), it is important to understand whether specific symptoms are stable over time or vary over the course of the disorder. This is the first longitudinal investigation examining the stability of the nine criterion symptoms of depression, as specified in the DSM-IV, among diagnosed depressed adults who were not recovered at follow-up. In this study, participants were assessed twice, ten months apart, with the structured clinical interview for DSM-IV, and stability of the nine criterion symptoms of MDD was examined. Findings indicate strong stability in individuals' symptom profiles. Among individuals who were clinically depressed at both assessments, there were no statistically significant fluctuations in specific symptoms endorsed. Changes in symptom endorsement among individuals who no longer met diagnostic criteria for MDD at Time 2 were attributable to reduced severity (i.e., number of symptoms) rather than to inconsistency of symptom endorsement. These results indicate that depressed individuals experience essentially the same pattern of specific symptoms over the course of a year. Variation in clinical course is likely to be attributable more to fluctuations in overall severity than to changes in specific symptoms of depression.