DD is the abbreviations of Dysthymic disorder, a form of depressive disorder characterized by at least 1 year (2 years in adults) of Depressed mood for more days than not, accompanie
d 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.
DD is also called or Dysthymia.