Suicide risk factors consistent across nations

NEW YORK (Reuters Health) - The largest study of suicidal behaviors ever conducted has found that 9.2 percent of the world's population has contemplated suicide, but fewer than 3 percent actually make an attempt.

And while the percentage of people who have considered suicide varies considerably from country to country, the overall risk factors -- being female, having less education, being younger, being unmarried and having mental disorders -- were the same across all of the 17 nations included in the analysis.

"Suicidal thoughts are not so infrequent if one in ten people, approximately, are having them," Dr. Matthew K. Nock of Harvard University in Cambridge, Massachusetts told Reuters Health. Nock is part of the World Health Organization's World Mental Health Survey Initiative, which is gathering mental health data via face-to-face interviews with people in 28 countries.

The current study, published in British Journal of Psychiatry, looked at suicidal behaviors including thoughts of suicide (known medically as suicidal ideation), having a suicide plan, and actually attempting suicide in 84,850 adults.

Suicidal thoughts were most common among New Zealanders, with 15.9 percent having considered suicide, closely followed by the US, with 15.3 percent. Italians were the least likely to consider suicide (3 percent), plan to kill themselves (0.7 percent), or attempt suicide (0.5 percent). Suicidal behaviors were also relatively rare in China and Nigeria.

The researchers found no difference in the prevalence of suicidal behaviors between rich nations as a group and middle- and low-income nations. And in all countries studied, mental health problems including mood disorders, impulse control disorders, anxiety disorders, and substance use disorders roughly tripled the likelihood of suicidal behaviors.

"We often think of depressive disorders as being strong risk factors for suicidal thoughts and behaviors," Nock noted. "What we found was that other disorders were just as strong."

He and his colleagues also found that while mood disorders were the most strongly tied to suicidal behaviors in high-income countries, impulse control disorders were more influential in low- and middle-income countries.

Another key finding, Nock said, was that people were much more likely to attempt suicide in the year after they first began having thoughts of doing so. And across all countries, adolescence was the highest-risk time for suicide attempts.

Nock and his colleagues are now investigating additional risk factors for suicide, as well as potential protective factors such as spirituality or social support, in the hopes of developing effective strategies for preventing suicidal behavior.

While some interventions have been found to be effective in research settings, he noted in an interview, these treatments have been slow to make their way into the real world of patient care. "There's a big gap between what we know and what we do," he said.

SOURCE: The British Journal of Psychiatry, February 2008.