This is what I was diagnosed with.
Dysthymia, also called neurotic depression, dysthymic disorder, or chronic depression, is a mood disorder consisting of the same cognitive and physical problems as in depression, with less severe but longer-lasting symptoms. The concept was coined by Robert Spitzer as a replacement for the term "depressive personality" in the late 1970s.
According to the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders, published in 1994 (DSM-IV), dysthymia is a serious state of chronic depression, which persists for at least two years (one year for children and adolescents). Dysthymia is less acuteand severe than major depressive disorder. As dysthymia is a chronic disorder, sufferers may experience symptoms for many years before it is diagnosed, if diagnosis occurs at all. As a result, they may believe that depression is a part of their character, so they may not even discuss their symptoms with doctors, family members, or friends.
Dysthymia often co-occurs with other mental disorders. A "double depression" is the occurrence of episodes of major depression in addition to dysthymia. Switching between periods of dysthymic moods and periods of hypomanic moods is indicative of cyclothymia, which is a mild variant of bipolar disorder.
In the DSM-5, dysthymia is replaced by persistent depressive disorder (PDD). This new condition includes both chronic major depressive disorder and the previous dysthymic disorder. The reason for this change is that there was no evidence for meaningful differences between these two conditions. The term is from Ancient Greek δυσθυμία meaning bad state of mind. ....
Since I began my memoir, I have not been afraid to admit to others that I have this condition or that I have been on medication for it. And I'm glad to see others who aren't ashamed to admit or talk about such things. It took me a long time to come to terms with my depression and to receive help, but I'm glad I have done so.