Although the majority of people who have depression do not die by suicide, having major depression does increase suicide risk compared to people without depression. The risk of death by suicide may, in part, be related to the severity of the depression.
New data on depression that has followed people over long periods of time suggests that about 2 percent of those people ever treated for depression in an outpatient setting will die by suicide. Among those ever treated for depression in an inpatient hospital setting, the rate of death by suicide is twice as high (4 percent). Those treated for depression as inpatients following suicide ideation or suicide attempts are about three times as likely to die by suicide (6 percent) as those who were only treated as outpatients. There are also dramatic gender differences in lifetime risk of suicide in depression. Whereas about 7 percent of men with a lifetime history of depression will die by suicide, only 1 percent of women with a lifetime history of depression will die by suicide.
Another way about thinking of suicide risk and depression is to examine the lives of people who have died by suicide and see what proportion of them were depressed. From that perspective, it is estimated that about 60 percent of people who commit suicide have had a mood disorder (e.g., major depression, bipolar disorder, dysthymia). Younger persons who kill themselves often have a substance abuse disorder, in addition to being depressed.
- Suicide Prevention (National Institutes of Mental Health)