Everyone feels sad or low sometimes, but these feelings usually pass with a little time. Depression—also called “clinical depression” or a “depressive disorder”—is a mood disorder that causes distressing symptoms that affect how you feel, think, and handle daily activities, such as sleeping, eating, or working. To be diagnosed with depression, symptoms must be present most of the day, nearly every day for at least 2 weeks.
Possible causes include a combination of biological, psychological, and social sources of distress. Increasingly, research suggests these factors may cause problems in brain function, including abnormal activity of certain neural circuits in the brain. The persistent feeling of sadness or loss of interest that characterizes major depression can lead to a range of behavioral and physical symptoms. These may include changes in sleep, appetite, energy level, concentration, daily behavior, or self-esteem. Depression can also be associated with thoughts of suicide.
The mainstay of treatment is usually medication, talk therapy, or a combination of the two. Increasingly, research suggests these treatments may normalize brain function associated with depression.