Higher Intelligence in childhood is linked to a longer life, a study suggests.

The study found having a high IQ in childhood lowered the risk of dying by age 79 from heart disease, stroke, smoking related cancers, respiratory disease and dementia. A team from the University examined the association between intelligence test scores measured at age 11 and leading causes of death in men and women up to age 79.

Their findings are based on data from 33,536 men and 32,229 women born in Scotland in 1936, who took a validated childhood intelligence test at age 11, and who could be linked to cause of death data up to December 2015.

Cause of death included coronary heart disease, stroke, specific cancers, respiratory disease, digestive disease, external causes (including suicide and death from injury), and dementia.

After taking account of several factors that could have influenced the results, such as age, sex and socioeconomic status, the researchers found that higher childhood intelligence was associated with a lower risk of death until age 79.

For example, a higher test score was associated with a 28 per cent reduced risk of death from respiratory disease, a 25 per cent reduced risk of death from coronary heart disease, and a 24 per cent reduced risk of death from stroke.

Other notable associations were seen for deaths from injury, smoking related cancers (particularly lung and stomach), digestive disease, and dementia. There was no evident association between childhood intelligence and death from cancers not related to smoking.

It is the largest study to date reporting causes of death in men and women across the life course, and the findings suggest that lifestyle, especially tobacco smoking, is an important component in the effect of intelligence on differences in mortality.

The study was published in The BMJ journal.

"This research project has taken several years to complete and covers a large dataset across Scotland. We don’t fully know yet why intelligence from childhood and longevity are related, and we are keeping an open mind. Lifestyles – eg not smoking – education, health literacy, less deprivation, and genetics might all play a part. Future studies would benefit from measures of the cumulative load of such risk factors over the life course," said professor Ian Deary, director of the Centre for Cognitive Ageing and Cognitive Epidemiology.