Some are classified in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) by specific symptoms: Major depressive disorder (often called major depression) Persistent depressive disorder (dysthymia) Other specified or unspecified depressive disorder Others are classified by etiology: Premenstrual dysphoric disorder Depressive disorder due to another medical condition Substance / medication-induced depressive disorder Depressive disorders occur at any age but typically develop during the mid teens, 20s, or 30s (see also Depressive Disorders in Children and Adolescents).