Children with high intelligence quotients (IQs) live longer, but it is not clear exactly what role IQ plays in longevity.

Previous studies have shown an association between IQ and mortality, but an explanation for that has proved elusive. Therefore, researchers studied 10,620 men and women from UK to find out the association between IQ and mortality. This is an important question because identifying those mechanisms would help in understanding the origins of health inequalities. IQs were tested of all the participants when they were 11 years old and were followed until they were 46 years old. The data regarding their education, occupation, marital status, body mass index (BMI) was collected.

It was found that IQ assessed in childhood at age 11 predicted mortality risk from age 11 to age 46, so that the risk of dying by midlife was one and a half times higher in individuals with low IQs compared to those with high IQs (3 percent versus 2 percent, respectively). Adult sociodemographic variables such as education, occupation, marital status and health behaviours such as smoking, weight, alcohol use and psychosomatic symptoms explained only relatively little of the IQ-mortality association.

The association between IQ and mortality were largely independent of several measures of childhood developmental characteristics and family background such as birth weight, childhood height at age 11, problem behaviour, father's occupation, parents' interest in child's education, family size and difficulties.

The researchers concluded that IQ is an important determinant of health and risk of dying independent of many well-established health risk factors. However, further studies are required to identify the mechanisms by, which IQ is associated with health and mortality risk.