Why do people consider killing themselves? What makes people transition from thinking about suicide to acting on it?
Nearly 1 million people die by suicide worldwide each year, according to the World Health Organization. That’s about 1 suicide every 40 seconds. In the United States, 38,000 people kill themselves annually. Nationally, suicide is the 10th leading cause of death and the third leading cause among adolescents and young adults. Yet despite public and private investments in suicide research, U.S. suicide rates have not noticeably decreased in decades, which signals a need for better methods to predict and prevent self-injurious intent and behavior.
Harvard University’s Dr. Matthew Nock
“Suicide is a huge problem for us philosophically, clinically, scientifically and as a society,” said Dr. Matthew K. Nock, professor of psychology and director of the Laboratory for Clinical and Developmental Research at Harvard University. “It’s something we really need to try to do a better job of understanding.”
Studies of suicide risk typically rely on retrospective self-reporting, which limits our ability to observe what triggers suicidal thoughts and how long they may last, argued Nock, who spoke at the NIMH Director’s Innovation Speaker Series recently. While we can cull important data and trends from these studies, he advocates the need for studies that reveal self-injurious intentions in real time.
Suicidal thoughts, or ideation, can be hard to measure. Such thoughts often are transient and patients might not reveal them during clinical exams. Also, people tend to deny or contain thoughts of suicide, said Nock, which may help explain why there’s such a spike in suicide deaths shortly after at-risk patients are discharged from a hospital.
One of the largest studies on suicidal behavior, the WHO World Mental Health Survey Initiative, which is funded in part by NIMH, is providing data on suicidal thoughts, plans and attempts across a large, nationally representative sample.
About 10,000 Americans were interviewed at length in their homes; the study is being replicated in more than 25 countries.
Based on responses from 85,000 adults in the 17 countries for which data has been analyzed, 9 percent of respondents have seriously considered killing themselves, 3 percent made suicide plans and almost 3 percent made attempts.
Rates are among the highest in the U.S., where 15 percent of adults reported having suicidal thoughts, 5 percent made suicide plans and 5 percent made attempts.
The findings look fairly consistent cross-nationally. Men are 4 times more likely to die by suicide in every country examined. Also, suicide risk is higher for those who are younger, unmarried or have mental disorders.
A prior mood disorder corresponded to a 4- to 6-fold increase in the odds of suicide ideation, plans or attempts. Interestingly, those suffering from depression were more likely to have suicidal thoughts but not to act on them. Nock said people with disorders characterized by agitation, anxiety, poor behavioral control or substance abuse were more likely to act on their suicidal thoughts.
Nock says, “Suicide is a huge problem for us philosophically, clinically, scientifically and as a society. It’s something we really need to try to do a better job of understanding.”
Photos: Ernie Branson
Similarly, a family history of depression or anxiety predicted onset and persistence of ideation but did not necessarily predict actions. Those whose parents had a history of panic or antisocial behavior had a higher risk of acting on their suicidal thoughts.
In this study, about one-third of people who had suicidal thoughts actually made a suicide plan or suicide attempt.
In every country examined, at least 60 percent of transition to suicide attempts happened within the first year after onset of ideation, said Nock. And consequently, the longer someone goes thinking about suicide without making a suicide attempt, the less likely that person is to make a suicide attempt.
Additional data show that about half to two-thirds of adolescents with ideation, plans or attempts were in treatment prior to onset. “As a society, we’re doing a good job of capturing those at risk and getting them into treatment before they become suicidal,” said Nock. “On the flip side, [despite treatment], they’re still thinking about suicide and making suicide attempts.”
While such studies reveal important clues to understanding the suicidal mind, Nock’s team is working to introduce more real-time monitoring studies to help assess self-destructive thoughts and behaviors as they occur among at-risk adolescents and young adults.
In one study, 30 adolescents ages 12-19 with a recent history of non-suicidal self-injury were asked to log entries into electronic diaries regularly for 2 weeks. Respondents reported thinking about self-injury more frequently and with greater intensity than they thought about suicide. About one-fifth of those who thought about self-injury also thought about drinking and drug use at the same time but weren’t actually drinking or using drugs at the time. Many reported feeling sad or overwhelmed during ideation. But those who reported feeling rejected, angry or self-hatred were the ones who made plans or attempts at self-injury.
While the sample size is small, this type of study can be an important tool in helping to identify markers of imminent risk. Current research is aimed at developing new cognitive tests and new interventions to decrease suicidal thinking.
There’s a great need, said Nock, to develop innovative ways to measure risk to ultimately improve suicide assessment and treatment.