Public health officials and scientists use the term "suicide contagion" to describe the spread of suicidal thoughts among a group of people that results in such copycat acts.
Suicide rarely occurs in a vacuum. Although the act itself may be impulsive, people who kill themselves usually have considered or tried it before. As many as 90% of suicide victims have a diagnosable and treatable mental disorder, such as major depression and alcohol or drug abuse. (However, only a tiny minority of depressed patients commit suicide.)
In addition to risk factors, there's usually a triggering event, such as the loss of a loved one or school troubles. In vulnerable individuals, such crises prompt feelings of shame, humiliation or despair, says Dr. David Litts, director of science and policy at the federally funded national Suicide Prevention Resource Center.
The same factors are thought to be at work in suicide clusters -- that a teen already in crisis is moved to act by exposure to a peer committing suicide. "It opens up possibilities that are not normally open," says Dr. Thomas Hicklin, a psychiatrist at USC's Keck School of Medicine.
An idea, in other words, is planted in an already susceptible mind.
Hicklin adds, "In studies we've done at USC, up to 40% of the suicide attempters express to us that their friend or relative or parent had attempted suicide." He's also heard children say, "I saw it on TV." And yet the scientific evidence on risk posed by suicide contagion is thin, in part because the number of potential study subjects -- vulnerable peers exposed to suicide contagion -- is few.
One might imagine that suicide risk would be greatest for those vulnerable teens who have had a close friend commit suicide. But some studies show that kids who were close to the victim actually may be at lower risk, not higher.
For example, a 1994 report in the Journal of the American Academy of Child and Adolescent Psychiatry assessed risk factors in 146 friends and acquaintances of 26 suicide victims and compared their responses to 146 matched subjects who had not been exposed to peer suicide.
When depression and past difficulties were taken into account, exposed teens actually had a lower rate of suicide attempts, says study author Dr. David Brent, a suicide expert at the Western Psychiatric Institute and Clinic of the University of Pittsburgh Medical Center.
"When we asked the kids about it, what they said is that they had considered suicide a lot in the past. But having confronted it face to face, and seeing what it did to them and their friends and family, they would never do it."
Brent says this observation -- that people who imitate tend not to be closely linked with the person they're imitating -- has been noted by other suicide researchers.
News reports have often been blamed for cases of suicide contagion, but the actual risk is hard to pin down. A series of studies in the early 1980s did find that suicide rates rose after news reports of a suicide appeared in newspapers and television. But the content of the reports may be crucial. Media attention on the loss of a young life can overly romanticize the victim at the cost of downplaying the prolonged doubt and pain to friends and family, the researchers concluded.
As a result, the American Foundation for Suicide Prevention ( www.afsp.org) and similar groups now have media guidelines that discourage reporters from using too much detail or graphic representations of suicides and from publishing too many stories about local or recent events. Reports, the guidelines say, should emphasize the fact that depression is a treatable mental illness and that those with suicidal thoughts can be helped.
However, other investigators have found that exposure to media reports does not always seem to play a role in suicide clusters. Researchers from the Centers for Disease Control and Prevention found no such link after investigating two suicide clusters that occurred in Texas in the early 1980s.
However, the report did find that teens who killed themselves were more likely to have made previous suicide threats or attempts, to have been hospitalized for mental illness or to have recently broken up with a girlfriend or boyfriend. In other words, they exhibited the same risk factors found for suicides that do not occur in clusters or among adolescents.
The CDC study identified other risk factors for suicide: frequent family moves, attending multiple schools and living with different parental figures. There are protective factors as well, suicide experts say, such as strong connections to a caring adult, whether a parent, teacher or coach, and a sense of belonging to one's community. "The stronger the connections are, the lower the risk," Litts says.
Brent estimates that in 5% to 10% of teenage suicides, some degree of contagion is at work. However, he's the first to admit it's a slippery business to identify it in most suicides. "It's really hard to prove that imitation has or hasn't happened," he says.
Most researchers agree that suicide is caused by many factors coming together in an individual, even when it occurs in a cluster with evidence of imitation, as in Palo Alto.
The CDC provides guidelines for schools or other communities about how to respond to one or more suicides, including identifying high-risk individuals and providing counseling. They also call for reducing any predisposing risks in the school environment, such as bullying or social isolation. Read more at www.cdc.gov/ ncipc/dvp/suicide/youth suicide.htm.