- Dysthymic disorder (DD) or Dysthymia : dysthymic disorder (DD) or dysthymia refers to a form of depressive disorder characterized by at least 1 year (2 years in adults) of depressed mood for more days than not that is accompanied by additional depressive symptoms that do not meet criteria for a major depressive episode. In comparison to Major depressive disorder, Dysthymia is milder, but more long-term.