<unk> , also known as persistent depressive disorder (PDD), is a mental and behavioral disorder, specifically a disorder primarily of mood, consisting of the same cognitive and physical problems as depression, but with longer-lasting symptoms. The concept was coined by Robert Spitzer as a replacement for the term "depressive personality" in the late 1970s. In the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV),<unk>  is a serious state of chronic depression, which persists for at least two years (one year for children and adolescents).<unk>  is less acute than major depressive disorder, but not necessarily less severe. As<unk>  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. In the DSM-5,<unk>  is replaced by persistent depressive disorder. This new condition includes both chronic major depressive disorder and the previous<unk>  disorder. The reason for this change is that there was no evidence for meaningful differences between these two conditions.
Dysthymia
Euthymia 
Cyclothymia
Myokymia
Congenital athymia
Minor depressive disorder
Atypical depression
Panic disorder