In the largest study of its kind ever undertaken, a team of researchers analyzed the medical records of more than one million men dating back over 24 years and compared rates of hospital admission for attempted suicide against IQ scores. They found that even after adjusting for factors such as age and socioeconomic status, men with lower IQ scores were significantly more likely to have attempted suicide. The findings appear in theBritish Medical Journal.
“We have found a clear link between IQ and attempted suicide in this group of men. In common with some previous, smaller studies, we have shown that men with lower scores have a markedly greater risk of attempted suicide than men of higher IQ,” noted researcher David Batty. He goes on to suggest a number of possible explanations that might underlie the association.
Firstly, low IQ tends to correlate with lower socioeconomic status and income, and so individuals with a lower IQ may experience more social and financial disadvantage, leading to an increase in suicidal thoughts and behaviors. Lower IQ has also been associated with poor health behaviors such as binge drinking, which also increases suicide risk. However, Batty says these factors are unlikely to fully explain the observed associations.
Another possible explanation, though one which the researchers were unable to investigate further, was the role of violence early in life. Exposure to violence early in life, either directly as a victim or indirectly as a witness has been previously shown to influence both IQ or academic performance and future risk of suicide or suicidal thoughts.
“Suicide, either attempted or actual, is a serious problem, particularly amongst young adults, but we have a relatively poor understanding of what leads a person to take such drastic action,” said co-researcher Elise Whitley. “If we can better understand the association between IQ and suicide, this will provide valuable insight into why some people make such a tragic decision.”