Classification of Depression According to the International Classification Diseases, Tenth Revision (ICD-10) Waleed Ahmad The ICD-10 has comprehensively sub-classified into various categories based on the clinical profile of symptoms and the course of symptoms.  Based on the course, it may be a depressive episode, recurrent (major) depressive disorder, persistent depressive disorder or dysthymia, recurrent brief depression, etc. Depression may also be either unipolar or bipolar or it may occur in   A first depressive episode, duration of at least15 days, is classified as a  depressive episode (F32).  If the first depressive episode severe and rapid onset, duration less than 15 days still depressive episode (F32).   A depressive episode can be mild (2 core symptoms, 2 other symptoms from the list) (32.0) moderate (2 core symptoms, 3 or preferably 4 other symptoms) (32.1) Severe (3 core symptoms, 4 other symptoms) without psychotic symptoms (32.2) (no delusion, hallucination or stupor)