Suicide is a widespread social problem that occurs in all human societies. In the United States in 2000, suicide was the eleventh leading cause of death. The total number of suicides was 29,350, or 1.2 percent of all deaths. In 2001, the figure was 30,622. Suicide is more common than murder. The problem goes even deeper than the statistics state, since it is estimated that for every death by suicide, there may be from eight to twenty-five attempted suicides.

Risk factors for suicide vary. More than 90 percent of people who kill themselves suffer from depression or some other mental disorder or from substance abuse. Suicide as well as depression are associated with lower levels of a brain chemical called serotonin. Medication aimed at relieving depression boosts serotonin levels.

Depression and suicide may also be a response to adverse and stressful life events, such as loss of a job...