Major depression: A disease with certain characteristic signs and symptoms that interferes with the ability to work, sleep, eat, and enjoy once pleasurable activities.
The characteristic signs and symptoms of major depression include loss of interest in activities that were once interesting or enjoyable, including sex; loss of appetite (anorexia) with weight loss or overeating with weight gain; loss of emotional expression (flat affect); a persistently sad, anxious or empty mood; feelings of hopelessness, pessimism, guilt, worthlessness, or helplessness; social withdrawal; unusual fatigue, low energy level, a feeling of being slowed down; sleep disturbance with insomnia, early-morning awakening, or oversleeping; trouble concentrating, remembering, or making decisions; unusual restlessness or irritability; persistent physical problems such as headaches, digestive disorders, or chronic pain that do not respond to treatment; thoughts of death or suicide or suicide attempts. Alcohol or drug abuse may be signs of depression.
Disabling episodes of major depression can occur once or a number of times in a lifetime.
For more information, see Depression.