Persistent depressive disorder (PDD, previously called dysthymia) is a mood disorder qualitatively similar to major depressive disorder (MDD) but with fewer and less severe symptoms that persist for much longer than the episodic symptoms of MDD. Specifically, in PDD the depressed mood and other symptoms are present most of the time on most days for at least two years. In addition, any symptom-free periods last no more than two months.
Because the symptoms may develop gradually and are not as dramatic as those of MDD, persistent depressive disorder often goes unnoticed. People may come to believe that they have always been that way. Nonetheless, it should not be thought of as a minor condition. Lack of treatment not only allows the needless continuation of both mental and physical suffering, but it places people at increased risk for subsequently developing MDD.
This article first appeared in the UC Berkeley Wellness Letter.
Also seeShining a Light on Depression.