A major study in Sweden has linked a lower IQ in early adulthood with a higher risk of suicide later in life.
The study was conducted by Dr Finn Rasmussen from the Department of Public Health Sciences at Karolinska Institute in Stockholm, along with colleagues in the UK and Australia.
Published in the British Medical Journal, it revealed that men with the lowest early adulthood IQ scores were almost nine times more likely to attempt suicide than those with the highest.
Dr Rasmussen looked at the medical records of over one million men aged between 16 and 57 and living in Sweden.
"Low IQ scores in early adulthood were associated with a subsequently increased risk of attempted suicide in men free from psychosis," concluded the study.
However, while a link was found, the scientists also suggested that the lower IQ scores may be related to other lifestyle choices such as habits including binge drinking.