Do mental disorders predict suicide attempts or suicidal thoughts more strongly?

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Suicide is a leading cause of death worldwide, and mental disorders are among its strongest predictors. Researchers asked which disorders uniquely predict suicidal behavior, how much they predict attempts beyond their association with suicidal thoughts, and whether these associations differ between developed and developing countries. They focused on nonfatal suicide attempts.

In the WHO World Mental Health Surveys, 108,664 respondents from 21 countries completed structured face-to-face interviews. The interviews collected information on the lifetime occurrence and age of onset of mental disorders defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV), and of nonfatal suicidal behaviors.

Every lifetime disorder examined significantly predicted a subsequent first suicide attempt, with odds ratios (ORs) of 2.9–8.9. After controlling for comorbidity, the associations decreased substantially to ORs of 1.5–5.6 but remained significant in most cases. Overall, mental disorders were equally predictive in developed and developing countries. The strongest predictors of suicide attempts differed, however: mood disorders in developed countries, and impulse-control, substance use and post-traumatic stress disorders in developing countries.

Breaking down the associations showed that they were largely due to disorders predicting the onset of suicidal thoughts rather than progression from thoughts to nonfatal attempts. A wide range of mental disorders was associated with increased odds of suicidal ideation. In the few instances where disorders predicted progression from thoughts to attempts, the significant disorders were characterized by anxiety and poor impulse control. After controlling for psychiatric comorbidity, only disorders with those characteristics predicted which people with suicidal ideation acted on their thoughts.

The researchers said the findings offer a more detailed understanding of associations between mental disorders and subsequent suicidal behavior and indicate similar prediction across developed and developing countries. Limitations included retrospective self-reports of lifetime occurrence and age of onset of disorders and suicidal behaviors, and the narrow focus on mental disorders as predictors of nonfatal suicidal behaviors. Future studies need to address these limitations and clarify the mechanisms by which people develop suicidal thoughts and then progress to attempts.