The disorder depression is a feeling of sadness intense enough to interfere with functioning. It may follow a recent loss or other sad event but is out of proportion to that event and lasts beyond an appropriate length of time.

  • Heredity, side effects of drugs, emotionally distressing events, imbalances in the body, and other factors can contribute to depression.
  • Depression can make people sad and sluggish or anxious and fearful.
  • Doctors base the diagnosis on symptoms.

After anxiety, depression is the most common mental health disorder. About 30% of people who visit a primary care practitioner have symptoms of depression. However, only some of these people have major depression. People who become depressed typically do so in their mid teens, 20s, or 30s, although depression can begin at almost any age, including during childhood.