Dysthymic Disorder (or ) is a chronic mood disorder that falls within the depression spectrum, the opposite of hyperthymia. It is considered a chronic depression, but with less severity than major depressive disorder. This disorder tends to be a chronic, long-lasting illness.Hersen, M., Turner, S. M., & Beidel, D. C. (Eds.). (2007). Adult Psychopathology and Diagnosis (5th ed.). Hoboken, New Jersey: John Wiley & Sons, Inc. Dysthymia is a type of low-grade depression. Harvard Health Publications… (More on Dysthymia)