But there is a chance that genetics may also play a role, a theory that suggests people whose DNA gives them high intelligence also likely to be healthier in other ways.
How the research was carried out
The researchers, whose work is published in the British Medical Journal, examined data for 33,536 men and 32,229 women born in Scotland in 1936.
Their intelligence was tested at age 11 and they were followed for 68 years until December 2015.
After taking account of several factors that could have influenced the results - such as age, sex and socio-economic status - the researchers found people who had displayed higher childhood intelligence were more likely to still be alive.
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 lower risk of death from stroke.
The researchers said several theories have been put forward as explanations, such as people with higher IQs being more likely to look after their health and being less likely to smoke.
They also tend to do more exercise and seek medical attention when ill.
Other evidence suggests genetics may play a role in the link between cognitive ability and longevity.
We should copy smart people
Professor Ian Deary of the University of Edinburgh, who led the research, said: 'I'm being optimistic about these results.
"I'm hoping it means that if we can find out what smart people do and copy them, then we have a chance of a slightly longer and healthier life.
"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. We and other research teams are testing these ideas."
Experts from the Karolinska Intitute in Sweden, writing in a linked editorial also published in the BMJ, said IQ seems to be most strongly linked to smoking.
"Importantly, it shows that childhood IQ is strongly associated with causes of death that are, to a great extent, dependent on already known risk factors," they wrote.
"Tobacco smoking and its distribution along the socioeconomic spectrum could be of particular importance here.
"It remains to be seen if this is the full story or if IQ signals something deeper, and possibly genetic, in its relation to longevity."
Childhood lead exposure linked with lower IQ
Lead exposure in childhood could be linked to lower IQs as adults, a recent study revealed.
Scientists say being exposed to extremely high levels of lead - whether through pollution, soil, or paint - is responsible for a "loss of intelligence" and occupational standing among today's adults.
Researchers from the University of Otago in New Zealand and Duke University in North Carolina looked at children born in two cities across two continents for more than 30 years.
For years, levels of lead in blood deemed to be unsafe in children were up to seven times higher than what is considered unsafe today.
This delay in recognizing what were dangerous levels means many children may have been denied treatment that could have aided in their growth and development.
