Beware jocks and mean girls: you may be more popular in high school, but according to a new academic paper, it is the smart kids and conscientious glee-club types who will live longer. Not only that, they will suffer fewer diseases before they die. Only the good die young? Guess again.
The paper, which was published recently in the journal Psychological Science in the Public Interest, summarizes data from millions of people studied in dozens of academic articles. The bottom line is that people who are smarter and more conscientious acquire fewer illnesses and die later than those who have the opposite traits.
How these relationships work is wildly complicated, but one of the simplest associations is between intelligence and health: smarter people are more adept at avoiding accidents, and they are more likely to understand public-health campaigns against smoking or drug abuse. Studies typically show that by middle age, there is a reliable correlation between low IQ and rate of hospital admission, even when researchers control for socioeconomic differences. (More on Time.com: Why Do Immigrants Live Longer Than Native-Born Americans? Smoking)
A more puzzling but just as reliable finding is that people of lower intelligence are more likely to have disorders that stem in large part from genes. For instance, the new paper quotes a 2010 finding that those who have IQ scores just one standard deviation lower than the mean have a 60% greater risk of being admitted to a hospital for schizophrenia. That could be because admitting staffs are biased against people they see as less intelligent, but low intelligence is also correlated with greater risk of alcohol problems, depression, anxiety, late-onset dementia and posttraumatic stress disorder — again, even after researchers control for class variances. The same goes for risk of death by suicide and homicide and risk of injury from fights, stabbings, or maulings with blunt instruments.
Some of these relationships can be explained simply: stupid people make stupid decisions. But no one decides to be schizophrenic or to have dementia (or, for that matter, to be mauled by a blunt instrument). The authors wonder, then, if there’s a genetic relationship between intelligence and likelihood of injury and earlier-than-average death.
How would that genetic relationship work? “One possibility,” write Ian Deary, Alexander Weiss and David Batty of the University of Edinburgh, “is that intelligence might capture suboptimal neurodevelopment.” Which would mean that the less intelligent have not only more limitations on their cognitive growth but that their very brains are constructed worse, leaving them more susceptible to physiological problems such as dementia.
Still, the strong relationship between lower intelligence and higher risk for illness also exists for non-brain ailments such as cardiovascular disease. According to a 30-year Scottish study published in 2004, a one standard-deviation disadvantage in intelligence at age 11 was related to an 11% increased risk of hospital admission or death due to cardiovascular illness. The Edinburgh team says this finding coincides with data from Denmark, Sweden, and the United States. Higher intelligence is also negatively correlated with risk of stroke. (More on Time.com: Why Smart Humans — and Honeybees — Live Longer)
The authors suggest the mechanism at work may be that less intelligent people have a harder time understanding the importance of physical activity, a heart-healthy diet, and avoiding cigarettes. This mechanism would explain why there is a correlation between intelligence and lung cancer but not between intelligence and most other kinds of cancers.
What about personality?
A seminal 1959 paper published in the Journal of the American Medical Association found that Type A people — hard drivers, people who face high competition and strict deadlines — are at higher risk for coronary heart disease. That finding is now so common that we take it for granted.
But it’s also true that cardiac patients with Type D personalities — those who lack confidence and are prone to irritability — are at substantially greater risk for poor outcomes including death, according to a 2006 study. By contrast, patients open to experiences (art, ideas, feelings) are at lower risk for cardiac mortality.
Studies have shown for nearly 20 years that the key personality trait that predicts longevity is conscientiousness. In one long-term study, students judged by their parents and teachers to be conscientious as 12-year-olds were more likely to be alive when researchers followed up 64 years later. Surprisingly, though, the same study found that cheerfulness was related to greater mortality risk, suggesting that happy, popular kids turn out to be at greater risk for disease later on, perhaps because they feel overly confident about their abilities to defeat life’s difficulties. (More on Time.com: Explaining Why Meditators May Live Longer)
High conscientiousness predicts a lower likelihood of developing all kinds of illnesses: diabetes, high blood pressure, hernia, bone problems, sciatica, stroke, Alzheimer’s and tuberculosis. More conscientious HIV patients also enjoy a slower progression of their disease as indicated by viral loads, perhaps because they learn from helping others why it’s important to care for themselves. As for other personality types, neurotic people tend to smoke more, as do ill-tempered people.
According to the Ediburgh team, a major flaw in these findings is that most of the studies that generated them did not adequately control for socioeconomic status (SES). Still, the authors write that the studies that did control for SES found that it “accounts for only a modest amount of the relationship between personality and health.”
Why is it that people with sunnier dispositions live longer? One reason may be that they interact more productively with health-care workers than do cynical, distrustful, or irritable people.
That’s fascinating, but what are we to make of all these findings? After all, the very project of relating intelligence or personality traits to health outcomes seems a bit elitist: we smart, self-assured people unencumbered by neurotic fears are going to outlive you mean strivers. (More on Time.com: Explaining Why Meditators May Live Longer)
As I was reading the careful data so attentively amassed by the Edinburgh team, I didn’t think I would find any such elitism. Then I got to the final few pages. That’s when the specter of eugenics crept into the discussion.
Here’s one scary passage: “A patient lower in intelligence or agreeableness or who displays a distressed type of personality could have his or her cardiovascular health monitored more regularly [than those higher in intelligence or agreeableness].” Really? And who decides who is more “agreeable?” How, exactly, do we force the stupid and the mean to get these cardiovascular tests?
Here’s another example:
When faced with a patient high in conscientiousness, a physician’s or nurse’s advice to change his or her diet or give up smoking would be likely to be met by a high self-directed effort on the part of the patient. However, for a patient low in conscientiousness, this advice may need to be accompanied with short-term incentives and regular monitoring and reminders or behavior modification either by the health-care provider or some other expert.
Wow. “Behavior modification?” “Regular monitoring” by doctors or unnamed “experts”? The authors seem to be suggesting a social-control model of dealing with people not quite as smart and optimistic as they are. People should have the right to make their own health-care decisions regardless of how smart and likable they are. Are we really going to have a separate health-care system for mean people? (More on Time.com: Middle Age: It’s Not Downhill from Here — At Least in Terms of Mood)
In short, let’s not take this paper beyond the cocktail party. Like so many academics obsessed with intelligence scores, the Edinburgh team sounds smart but may be just creepy.