Possible causes include a combination of biological, psychological, and social sources of distress. Increasingly, research suggests these factors may cause changes in brain function, including altered 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 changes associated with depression.
Consult a doctor for medical advice
Sources: Mayo Clinic and others.
More than 3 million US cases per year
Treatable by a medical professional
Medium-term: resolves within months
Requires a medical diagnosis
Lab tests or imaging rarely required