Ten-year prospective follow-up study of the naturalistic course of dysthymic disorder and double depression.
OBJECTIVE
The purpose of this study was to describe the 10-year course and outcome of dysthymic disorder.


METHODS
The authors conducted a naturalistic, prospective, longitudinal follow-up of 97 adults with early-onset dysthymic disorder and 45 adults with nonchronic major depressive disorder selected from consecutive admissions to several outpatient facilities. Follow-up data were obtained for 90% of the cohort. Assessments were conducted at baseline, 30, 60, 90, and 120 months. Measures included the Longitudinal Interval Follow-Up Evaluation and the Hamilton Depression Rating Scale.


RESULTS
The Kaplan-Meier estimated recovery rate from dysthymic disorder was 73.9%, with a median time to recovery of 52 months. Among patients who recovered, the estimated risk of relapse into another period of chronic depression was 71.4%. Chronic depressive relapses took a variety of forms and were not limited to dysthymia. Nonetheless, the distinction between chronic and nonchronic forms of depression was relatively stable over the follow-up period. Mixed-effects models indicated that patients with dysthymic disorder experienced a significantly slower rate of improvement in symptoms over time and exhibited significantly greater depression at the 10-year point, compared to patients with nonchronic major depression.


CONCLUSIONS
Dysthymic disorder has a protracted course and is associated with a high risk of relapse. The nature of chronic depressive episodes varies over time within individuals, indicating that the various manifestations of chronic depression in DSM-IV do not represent distinct disorders. However, the distinction between chronic and nonchronic forms of depression is relatively stable and may provide a useful basis for subtyping in genetic and neurobiological research.
Klein
Daniel N
DN
Department of Psychology, Stony Brook University, Stony Brook, NY 11794-2500, USA. daniel.klein@stonybrook.edu
Shankman
Stewart A
SA
Rose
Suzanne
S
D000328:Adult; D017668:Age of Onset; D002908:Chronic Disease; D015331:Cohort Studies; D015897:Comorbidity; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D019263:Dysthymic Disorder / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D012008:Recurrence; D012307:Risk Factors; D012720:Severity of Illness Index; D016019:Survival Analysis; D009626:Terminology as Topic