Persistent Depressive Disorder, Dysthymia, and Chronic Depression: Update on Diagnosis, Treatment

Since the classic descriptions, depression has been conceived as an episodic and recurrent illness. Depressive episodes with clear onset and offset and sharp contrast with one’s usual mood and behaviors are perhaps the most conspicuous feature of severe mood disorders. However, systematic studies of unselected samples have been telling a different story: a large proportion of individuals suffer from low mood, lack of interest, and other symptoms of depression chronically, with some fluctuations but no clearly demarcated episodes.1 Chronic patterns of symptoms are often under-recognized and undertreated in the community.2