Study done on Scots pupils in 1947 links high IQ and long life

A study based on intelligence tests given to every available 11-year-old pupil at school in Scotland in 1947 has found that higher IQ in childhood is linked to a longer life.

A team of researchers from the University of Edinburgh set out to examine 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 test and who could be linked to cause of death data up to December 2015. The study is the largest of its kind to date and found higher intelligence is linked with a lower lifetime risk of major causes of death, including heart disease, stroke, smoking-related cancers, respiratory disease and dementia. On 4 June 1947, around 94 per cent of Scots born in 1936 who were registered as attending school completed a test of general intelligence, involving the administration of the Moray House test No 12, which had 71 parts tapping verbal and non-verbal reasoning ability.

After taking account of several factors that could have influenced the results, such as age, sex and socioeconomic status, the researchers found higher childhood intelligence was linked 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.

Professor Ian Deary of the University of Edinburgh, who led the research, said: “This ambitious research project took my team several years to complete, and it could only have been done in Scotland. Almost all women and men born in 1936 took the same intelligence test at age 11, and they were anonymously linked to causes of death up to their late 70s.

“The increased risk of dying earlier from many different causes is not just about low versus high IQ scorers; the benefit seems to increase all the way up the intelligence scale, so that very smart people live slightly longer than smart people, who live slightly longer than averagely-intelligent people, and so on.”