In 1996, the most recent year for which statistics are available, suicide was the ninth leading cause of death in the United States. Specifically, 10.8 out of every 100,000 persons died by suicide. It was estimated that there were 500,000 suicide attempts. Taken together, the numbers of suicide deaths and attempts reflect the magnitude of the problem and the need for well-designed prevention efforts.
Suicidal behavior is complex.
Some risk factors vary with age, gender and ethnic group and may even change over time. The risk factors for suicide frequently occur in combination. Research has shown that 90 percent of people who kill themselves have depression or another diagnosable mental or substance abuse disorder. In addition, research has shown that alterations in neurotransmitters such as serotonin are associated with the risk for suicide. Diminished levels have been found in patients with depression, impulsive disorders, a history of violent suicide attempts, and also in postmortem brains of suicide victims.