THURSDAY, June 3, 2010 (Health.com) — Young men with low IQs are much more likely than their peers to attempt suicide later in life, a new study has found. In fact, men with the lowest IQs are about four times more likely to attempt suicide as those with the highest, and the risk tends to go up as IQ drops.
This may seem surprising to those who associate suicide with tortured geniuses like Ernest Hemingway and Vincent Van Gogh.
“There’s a perception that people with higher IQs might be more neurotic, more anxious, and more depressed—Woody Allen style,” says Karestan Koenen, PhD, a clinical psychologist and associate professor at the Harvard School of Public Health.
“But the literature is very consistent that people with lower IQs are at increased risk not just of mental health problems, but of all kinds of physical health problems,” adds Koenen, who was not involved in the new study but has researched IQ and mental health.
In the study, which was published on the website of the British Medical Journal, researchers followed 1.1 million male military recruits in Sweden for an average of 24 years. All of the men took a standardized IQ test between the ages of 16 and 25.
The attempted suicide rate rose steadily as IQ scores fell, the researchers found. Of the men who had the highest score on the test, roughly 1 in 200 attempted suicide during the study; among the men with the lowest score, the rate was about 1 in 22. (The overall rate in the study was 1.6%, or about 1 in 60.)
When the researchers factored in the men’s age, they found that the men with the lowest IQ were nearly nine times more likely to try killing themselves than the men with the highest IQ.
Even after other factors that may influence suicide risk were taken into account—such as socioeconomic status, education, and even body mass index—the men with the lowest IQ were still about 3.5 times more likely to attempt suicide.
“We’re not talking about a hospital group or a sick population, so these findings are generalizable to the general population,” says the lead author of the study, David Batty, PhD, a Wellcome Trust Fellow at the Medical Research Council, in Glasgow, Scotland. The Wellcome Trust funded the study.
However, Batty and his colleagues point out that the findings may not necessarily apply to women, to older men, or to men in other countries. And there was no apparent link between IQ and suicide attempts in men with psychosis, they note.
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