Study Finds Link Between Higher Intelligence and Longer Life
While epidemiological research has stated for a while now that lifestyle affects lifespan, researchers have also discovered that higher intelligence translates on average to a longer life.
Writing in Scientific American, David Z. Hambrick, a professor in the Department of Psychology at Michigan State University, notes the work of Ian Deary and his colleagues at the University of Edinburgh using data from Scottish Mental Surveys to track the relationship. The survey was administered in 1932 by the Scottish government in the form of an IQ test presented to nearly all 11-year-old children attending school in a single day.
Deary and colleague Lawrence Whalley set out to identify who from the cohort was still alive, at age 76 some 60 years later, focusing on the city of Aberdeen, and they were stunned by what they found.
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A 15-point IQ advantage translated into a 21 percent greater chance of survival. A person with an IQ of 115, for example, was 21 percent more likely to be alive at age 76 than a person with an IQ of 100, which is the average for the general population.
This link between IQ and mortality has since been replicated more than 20 times in longitudinal studies around the world and has given rise to a field called cognitive epidemiology. It is the study of intelligence — as measured using psychometric tests — as an associate of mortality, illness, and health.
Evidence from research suggests that genes may contribute to the link between IQ and living a long life but an exact explanation of this link is still unclear. A new study by Rosalind Arden and colleagues in the International Journal of Epidemiology highlight the first evidence for this hypothesis.
"Exactly what could explain the genetic link between IQ and mortality remains unclear. One possibility is that a higher IQ contributes to optimal health behaviors, such as exercising, wearing a seatbelt, and not smoking. Consistent with this hypothesis, in the Scottish data, there was no relationship between IQ and smoking behavior in the 1930s and 1940s, when the health risks of smoking were unknown, but after that, people with higher IQs were more likely to quit smoking. Alternatively, it could be that some of the same genetic factors contribute to variation in both IQ and in the propensity to engage in these sorts of behaviors," noted Hambrick.
"These and other findings from cognitive epidemiology have potentially profound implications for public health. Along with factors such as family history of disease, IQ could be used proactively to assess people's risk for developing health problems and early death," he explained.
"At the same time, this potential use of intelligence tests raises ethical questions. As intelligence researchers are quick to point out, IQ doesn't reflect one thing — it reflects many things. This includes not only what you might think of as native' intelligence — brain regions like the prefrontal cortex — but a myriad of 'non-ability' factors. For example, there is evidence that a person's beliefs about their ability to do well on an intelligence test, which may be tied to their ethnicity or gender, can impact how well that person actually does on the test. In turn, being labeled 'low IQ' or 'high IQ' may impact a person's sense of self-worth," he added.
