Some 10 to 14 million people in the United States, and some 10 to 20 percent of the world's population, suffer from serious depression. It may result from the loss of a friend or relative, or a job, or from failing in some important function in life. Some believe that depression also can be caused by experiences in childhood, while others believe the cause lies in a chemical imbalance. Depressed people may experience loss of appetite for food and pleasure, insomnia, fatigue, feelings of worthlessness or guilt, an inability to concentrate, and recurring thoughts of death and/or suicide.
