出處：International Association for Suicide Prevention(2006). Information Flyer of 2006 World Suicide Prevention Day.
Already in this new century there have been more than 5 million suicide deaths worldwide. Each year approximately one million people in the world die by suicide.
In addition, it is estimated that there are from 10-20 times as many suicide attempts as suicide deaths.
This research suggests that suicidal behaviour is a complex issue, with multiple and inter-related causes. Mental illness is the most important factor that predisposes people to suicidal behaviour. People with mental illness have a 10-fold increased risk of suicide compared with people without such illness. In most Western countries almost 90% of people who die by suicide have a diagnosable mental disorder. The mental disorders most commonly associated with suicidal behaviour are depression and bipolar disorder, alcohol and substance abuse and schizophrenia. Of these, depression is the most common, and two thirds of those who die by suicide have a depressive illness at the time they die.