Dysthymia is a chronic and incapacitating form of depression that affects a substantial portion of the population (3-6%) and increases the risk for major depressive disorder. It is associated with significant disabilities and high comorbidity. The nosological status of dysthymia has been associated with considerable controversy over the past decades: some investigators regard it as a mood disorder, and others as a personality disorder. Currently classified among the mood disorders, dysthymia is now a treatable disorder and should receive more attention in view of its associated morbidity. The present article reviews the main historic aspects of dysthymia, its nosological features and its relationship with major depressive disorder. We conclude that further studies are necessary in order to validate the concept of dysthymia and the spectrum of chronic diseases, in order to provide a better understanding of the disorder as well as evidence-based guidelines.
Dysthymia; depression; mood disorders; comorbidity; historical and nosological aspects