Depression
Major depressive disorder, also known as major depression, unipolar depression, unipolar disorder, clinical depression, or simply depression, is a mental disorder characterized by a pervasive low mood and loss of interest or pleasure in usual activities. The diagnosis is made if a person has suffered one or more major depressive episodes. Diagnosis is based on the patient's self-reported experiences and observed behavior. There is no laboratory test for major depression, although physicians often test for physical conditions that may cause similar symptoms before arriving at a diagnosis. The course varies widely, from a one-off occurrence to a lifelong disorder with recurrent episodes. The most common time of onset is between the ages of 30 and 40, with a later peak between 50 and 60. The condition appears to be more common in women.