Symptoms:

• Agitation, restlessness, and irritability
• Dramatic change in appetite, often with weight gain or loss
• Extreme difficulty concentrating
• Fatigue and lack of energy
• Feelings of hopelessness and helplessness
• Feelings of worthlessness, self-hate, and inappropriate guilt
• Inactivity and withdrawal from usual activities, a loss of interest or pleasure in activities that were once enjoyed (such as sex)
• Thoughts of death or suicide
• Trouble sleeping or excessive sleeping

Depression can appear as anger and discouragement, rather than as feelings of hopelessness and helplessness. If depression is very severe, there may also be psychotic symptoms, such as hallucinations and delusions. These symptoms may focus on themes of guilt, inadequacy, or disease.

Signs and tests:

Major depression is diagnosed if a person reports having five or more depressive symptoms for at least 2 weeks. Beck's Depression Scale Inventory or other screening tests for depression can be helpful in making the diagnosis.

Before diagnosing depression, the health care provider should rule out medical conditions that can cause symptoms of depression.