Risk factors for suicidal thoughts, plans and attempts are consistent across countries, and include having a mental disorder and being female, younger, less educated, and unmarried. So says new research from a Harvard University professor and the World Health Organization (WHO) World Mental Health Survey Initiative. The study examined both the prevalence and the risk factors for suicide across 17 countries, and is the largest, most representative examination of suicidal behavior ever conducted.

Published in the February issue of the “British Journal of Psychiatry,” the study was led by Matthew Nock, associate professor of psychology in the Faculty of Arts and Sciences at Harvard, with data collected by the WHO World Mental Health Survey Initiative.

“Our research suggests that suicidal thoughts and behaviors are more common than one might think, and also that key risk factors for these behaviors are quite consistent across many different countries around the world,” says Nock.

Among those interviewed, 9.2 percent reported that they had seriously thought about suicide and 2.7 percent reported making a suicide attempt at some point in their lives. However, there was variation from country to country with regard to the rates of suicidal thoughts and behaviors. For instance, rates of suicidal thoughts ranged from 3.1 percent of people in China to 15.9 percent in New Zealand. A possible reason for this variation may be that different cultural standards exist with regard to the acceptability of telling others about suicidal thoughts. Therefore, among countries with lower rates of suicidal thoughts, it’s possible that some thoughts of suicide were not reported.

Across the countries included in the study, risk factors for suicidal behavior included female gender, younger age, fewer years of education, unmarried status and the presence of a mental disorder. Additionally, the risk of suicidal thoughts increased sharply during adolescence and young adulthood in every country studied.

The strongest risk factor associated with suicidal thoughts and behaviors were mood disorders in high income countries and impulse control disorders in low- and middle-income countries.

“We often think of suicidal thoughts and behaviors as occurring among people who are depressed, but across all of these countries, we found that it is not just depression that increases the risk of suicidal behaviors—impulse control disorders, substance use disorders, and anxiety disorders all are associated with a significantly higher risk of suicidal thoughts and attempts,” says Nock.

In fact, this study showed that among people with suicidal thoughts, the risk of making an attempt was highest not among those with a mood disorder, but in those with substance abuse and impulse-control disorders, suggesting that these disorders are most strongly associated with acting on suicidal thoughts when they are present.

Among other interesting findings in the study was that among people with suicidal thoughts, 29 percent later made a suicide attempt, and these attempts occurred most often within the first year after the onset of suicidal thoughts. The probability of a suicide attempt among people with both suicidal thoughts and a plan was 56 percent, but only 15.4 percent among those without a plan.

The survey included data from 17 countries: Nigeria, South Africa, Colombia, Mexico, USA, Japan, New Zealand, China, Belgium, France, Germany, Italy, the Netherlands, Spain, Ukraine, Israel and Lebanon. A total of 84,850 adults were asked about suicidal behaviors and socio-demographic and psychiatric risk factors.

Previous studies of suicidal behavior have largely relied on smaller, self-selected samples of suicidal individuals, and so it has been unclear how well the results would generalize in different countries around the world. This study is the first to examine the thoughts and behaviors of individuals across numerous, diverse countries.

Suicide is a leading cause of death worldwide, but information on its prevalence and risk factors is unavailable in many countries, particularly in those that are less developed. Currently, resources devoted to the treatment of mental disorders and to suicide prevention are lacking in many countries. Further research could help to explain the differences in prevalence of suicide thoughts across different countries, Nock says.

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Co-authors of the paper, all from the WHO World Mental Health Survey Initiative, were Guilherme Borges, Evelyn J. Bromet, Jordi Alonso, Matthias Angermeyer, Annette Beautrais, Ronny Bruffaerts, Wai Tat Chiu, Giovanni de Girolamo, Semyon Gluzman, Ron de Graaf, Oye Gureje, Josep Maria Haro, Yueqin Huang, Elie Karam, Ronald C. Kessler, Jean Pierre Lepine, Daphna Levinson, Maria Elena Medina-Mora, Yutaka Ono, Jose´ Posada-Villa and David Williams.

The research was funded by the National Institute of Mental Health, the John D. and Catherine T. MacArthur Foundation, the Pfizer Foundation, the U.S. Public Health Service, the Fogarty International Center, the Pan American Health Organization, Eli Lilly, Ortho-McNeil Pharmaceutical, GlaxoSmithKline, and Bristol-Meyers Squibb.

Contact: Amy Lavoie
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Harvard University