Dysthymia, now more commonly referred to as Persistent Depressive Disorder (PDD), is a chronic form of depression characterized by a low mood lasting for at least two years in adults (or one year ...

up to 25% of people developing MDD have a pre-existing dysthymic disorder. Left untreated, a typical episode of major depression will run approximately 6 months; about 20% of episodes can last 2 ...