New graduates of Fayetteville State University last month in North Carolina. A college degree is linked to higher life expectancy, but does it cause it?CreditTravis Dove for The New York Times
Education is associated with better health outcomes, but trying to figure out whether it actually causes better health is tricky.
People with at least some college education have mortality rates (deaths per 1,000 individuals per year) less than half of those without any college education, according to the Centers for Disease Control and Prevention.
In addition, people who are more educated exhibit less anxiety and depression, have fewer functional limitations, and are less likely to have a serious health condition like diabetes, cardiovascular disease or asthma.
But causality runs both ways. People in poor health from a young age may be unable to pursue education as much as those with better health. On the other hand, a person who tends to focus on long-term outcomes may be motivated to develop healthier habits like regular exercise — even if blocked from a pursuit of higher education.
Some clever studies have teased out the causal effects of education by exploiting natural experiments. One, by the U.C.L.A economist Adriana Lleras-Muney, relied on state compulsory education laws enacted between 1915 and 1939. These laws required some children to obtain more education than they might have otherwise, resulting in longer lives for those that did so. According to the study, having an additional year of education by 1960 increased life expectancy at age 35 by 1.7 years.
Studies that relied on inducements for greater education because of a poor labor market or as a way to avoid the Vietnam draft found that increased education led to better health and a lower likelihood of smoking. This finding is one clue about how education may improve health. It can reduce people’s engagement in risky behaviors, perhaps because those behaviors could threaten the higher income that greater education typically confers.
But health behaviors can explain only a portion of the relationship between education and mortality. Education may also provide skills to analyze information and tackle complex problems — precisely what’s needed to navigate the modern health system and attend to chronic diseases.
A higher level of education is also associated with higher income and greater wealth, which are also correlated with better health.
Again, causality goes both ways. You have to be reasonably healthy to keep a job or to work long hours, for example. But higher income also often comes with better health insurance and easier access to health care.
Much of income’s effect on health may originate in childhood. Many studies demonstrate that children of wealthier parents are in better health, perhaps because of better access to prenatal care and nutrition, or because they live in less polluted environments. A healthier childhood often means a healthier adulthood. And children born to higher-income parents are more likely to obtain more education and have higher incomes themselves. That’s how the income-health relationship may propagate across generations.
Greater education and wealth can also confer greater social status or rank, which has also been linked to health. A landmark study published in 1978 found that higher-ranking British civil servants (like administrators) had lower rates of mortality due to coronary heart disease than lower-ranking ones (like messengers). Lower-ranked civil servants tended to be heavier; they had higher blood pressure and blood sugar, and smoked more. Many investigations have replicated this relationship between social rank and health.
An intriguing hypothesis that links social standing and health is that people of lower status lead more stressful lives. Stress is known to alter blood flow and release hormones damaging to tissue, suppressing the immune system and raising risks of cardiovascular disease and mortality. One study linked childhood poverty to chronic stress and subsequent reductions in memory, which could affect education, wage attainment and health. Even stress endured in pregnancy can affect the health of the fetus in ways that endure throughout life, research suggests.
Health also varies by racial and ethnic identity, which also tend to play a big role in social standing.
For example, African-Americans have higher rates of mortality than white Americans, even after adjusting for income and education. Here too, there are childhood origins — African-American infants are more likely to be born preterm and with lower birth weights.
One reason may be less access to prenatal care. African-American patients are also less likely to receive preventive health care and more likely to live in areas with lower-quality hospitals and doctors. Disadvantages and stress stemming from a history of discrimination and community segregation underlie these and other disparities.
Hispanics tend to be healthier than comparable non-Hispanic white Americans, despite being poorer on average. The Hispanic paradox, as it’s known, could be because Hispanic immigrants are typically in better health than native U.S. residents (people who are healthier in the first place may be more likely to migrate). Or it could be because of health behaviors. For example, Hispanics are less likely to smoke or drink frequently than their white counterparts.
In this century, there has been a sharp rise in so-called deaths of despair — suicides, drug overdoses or alcohol abuse — for middle-aged white Americans without a college degree. Even as mortality rates for the poorly educated have risen, the rates among those with some college education have held nearly steady or gone down since 2007.
In 2012, researchers found that life expectancy for white women without a high school diploma was 73.5 years compared with 83.9 years for white women with a college degree or more. For white men, it was 67.5 years for those without a diploma compared with 80.4 for those with a college degree or better.
Just as our health is affected by lifestyle, genes, the environment and the health system, education has a role, too. We can’t yet say exactly how much or exactly why. But a decrease in longevity associated with lower education levels may help explain why overall American life expectancy has declined slightly in recent years — and fallen well off the pace of progress of most other advanced nations.