Smarter people are also healthier. That's the implication of new research, which finds a strong link between intelligence, as measured in childhood, and lower mortality rates throughout one's lifespan.
While that association has been noted before, the study, published in The BMJ, confirms and refines it in two important ways. It traces its subjects all the way to age 79, and finds the apparent protective effect of intelligence continues far into old age.
Furthermore, it finds the differences in mortality rates cannot be attributed entirely to the fact intelligent people are less likely to smoke, and tend to enjoy a higher economic status. While those factors play a major role, they aren't the entire story.
The study featured data on 33,536 men and 32,229 women, all of whom were born in Scotland in 1936, and completed a standard intelligence test in 1947, at age 11. The test featured 71 items "tapping verbal and non-verbal reasoning ability."
The researchers followed them for 68 years, noting who had died, at what age, and of what cause.
"Childhood intelligence was inversely associated with all major causes of death," reports the research team, led by University of Edinburgh psychologist Catherine Calvin. It specifically found higher scores "were associated with lower risk of mortality ascribed to coronary heart disease and stroke, cancers related to smoking (particularly lung and stomach), respiratory diseases, digestive diseases, injury, and dementia."
Rest assured, high-school brainiacs. You may be mocked as nerds today, but you'll probably live longer than your C-plus peers.
They found no relationship between intelligence and non-smoking-related cancers.
"The strongest associations we observed were for natural causes of death related to coronary heart disease, stroke, respiratory disease, lung cancer, and stomach cancer," the researchers report. "Smoking is a modifiable risk factor in each of these diseases, and higher intelligence has been related to lower likelihood of current smoking ... and the increased likelihood of quitting smoking."
Nevertheless, analysis of a replication sample that included information on participants' smoking habits found tobacco use, or the lack thereof, only partially accounted for the lower morality rates.
The researchers suggest working-class occupations, such as jobs in factories or in mines, are a possible contributing factor, especially for respiratory diseases. That said, they found the link between childhood intelligence and lower mortality rates remains even after social class is taken into account.
So the mechanisms behind these findings remain murky. Future studies that look more closely into lifestyle, including alcohol use and abuse, may add clarity.
But for now, rest assured, high-school brainiacs. You may be mocked as nerds today, but you'll probably live longer than your C-plus peers.