Suicide is usually caused by a combination of factors. Researchers have identified a number of risk factors associated with a higher risk for suicide and protective factors that may reduce the probability of suicidal behavior. The importance these factors can vary by age, gender, and ethnicity.
The impact of some risk factors can be reduced by interventions (such as providing effective treatments for depressive illness).
Those risk factors that cannot be changed (such as a previous suicide attempt) can alert others to the heightened risk of suicide during periods of a mental or substance abuse disorder, or a significant stressful life event.
The National Youth Violence Prevention Resource Center reports that other risk factors for suicide among teens are mental disorders (esp. depression) and substance abuse. Multiple studies from the US and Europe show that over 90 percent of people who complete suicide had a pre-existing diagnosable mental health or substance abuse disorder, especially depression.
In a 10- to 15-year follow-up study of 73 adolescents diagnosed with major depression, 7 percent of the adolescents had completed suicide sometime later. The depressed adolescents were five times more likely to have attempted suicide as well, compared with a control group of same-age peers without depression. Almost half of teenagers who complete suicide have had a previous contact with a mental health professional. In addition, aggressive, disruptive, and impulsive behavior is common in youth of both sexes who complete suicide.
Previous suicide attempt
If a youth has attempted suicide in the past, he or she is much more likely than other youths to attempt suicide again in the future. If a male teen has attempted suicide in the past, he is more than thirty times more likely to complete suicide, while a female with a past attempt has about three times the risk. About a third of teenage suicide victims have made a previous suicide attempt. While it was once thought that teen suicide was unpredictable, we now know we can identify risk factors in advance and intervene.
Family history
A high proportion of suicides and attempters have had a close family member (sibling, parent, aunt, uncle, or grandparent) who attempted or completed suicide. Familial suicide can be a function of imitation or genetics. Many of the mental illnesses which contribute to suicide risk appear to have a genetic component.
Impulsive and aggressive behavior
Youth who exhibit impulsive and aggressive behavior are more likely to attempt or complete. They rarely plan for a suicide, but are more likely to act on impulse.
Access to means (e.g. firearms)
The most common location of firearm suicides by youth is in their homes, and there is a link between the accessibility and availability of firearms in the home and the risk for youth suicide. If a child is talking about death or dying, one should remove all other means from the home, such as medications.
Exposure of suicide by others
Suicide can be aided in vulnerable teens by exposure to real or fictional accounts of suicide, including media coverage of suicide (such as intensive reporting of the suicide of a celebrity) or the fictional representation of a suicide in a popular movie or TV show. In addition, there is evidence of suicide clusters: local incidents of suicide that have a contagious influence. Suicide clusters nearly always involve previously disturbed young people who knew about each other's death but rarely knew the other victims personally.
Sexual Orientation
It has been widely reported in the media that gay and lesbian youth are at higher risk to complete suicide than other youth and that a significant percent of all attempted or completed youth suicides are related to issues of sexual identity. However, there are no national statistics for suicide completion rates among gay, lesbian or bisexual persons, and in the few studies examining risk factors for suicide completion where an attempt was made to assess sexual orientation, the risk for gay or lesbian persons did not appear any greater than among heterosexuals, once mental and substance abuse disorders were taken into account. With regard to suicide attempts, several state and national studies have reported that high school students who report engaging in homosexual or bisexual activity have higher rates of suicide thoughts and attempts compared to youth with heterosexual experience.
Experts have not been in complete agreement about the best way to measure reports of adolescent suicide attempts or sexual orientation, however, so the data are subject to question. Clearly, further research is needed in this area.