Thursday, January 04, 2007

A Surprising Secret to a Long Life: Stay in School
January 3, 2007
The New York Times

James Smith, a health economist at the RAND Corporation, has heard a variety of hypotheses about what it takes to live a long life — money, lack of stress, a loving family, lots of friends. But he has been a skeptic.

Yes, he says, it is clear that on average some groups in every society live longer than others. The rich live longer than the poor, whites live longer than blacks in the United States. Longevity, in general, is not evenly distributed in the population. But what, he asks, is cause and what is effect? And how can they be disentangled? [...]

The one social factor that researchers agree is consistently linked to longer lives in every country where it has been studied is education. It is more important than race; it obliterates any effects of income.

Year after year, in study after study, says Richard Hodes, director of the National Institute on Aging, education “keeps coming up.”

And, health economists say, those factors that are popularly believed to be crucial — money and health insurance, for example, pale in comparison.

Dr. Smith explains [that health insurance] “is vastly overrated in the policy debate.”

Instead, Dr. Smith and others say, what may make the biggest difference is keeping young people in school. A few extra years of school is associated with extra years of life and vastly improved health decades later, in old age.

It is not the only factor, of course.

There is smoking, which sharply curtails life span. There is a connection between having a network of friends and family and living a long and healthy life. [...]

Graduate Student Finds Answer

[In 1999] a Columbia University graduate student, Adriana Lleras-Muney, was casting about for a topic for her doctoral dissertation in economics. She found an idea in a paper published in 1969. Three economists noted the correlation between education and health and gave some advice: If you want to improve health, you will get more return by investing in education than by investing in medical care.

It had been an inflammatory statement, Dr. Lleras-Muney says. And for good reason. It could only be true if education in and of itself caused good health.

But there were at least two other possibilities.

Maybe sick children did not go to school, or dropped out early because they were ill. Or maybe education was a proxy for wealth, and it was wealth that led to health. It could be that richer parents who gave their children everything, including better nutrition, better medical care and a better education, had children who, by virtue of being wealthy, lived longer.

How, she asked herself, could she sort out causes and effects? It was the chicken-and-egg problem that plagues such research.

The answer came one day when Dr. Lleras-Muney was reading another economics paper. It indicated that about 100 years ago, different states started passing laws forcing children to go to school for longer periods. She knew what to do.

“The idea was, when a state changed compulsory schooling from, say, six years to seven years, would the people who were forced to go to school for six years live as long as the people the next year who had to go for seven years,” Dr. Lleras-Muney asked.

All she would have to do was to go back and find the laws in the different states and then use data from the census to find out how long people lived before and after the law in each state was changed.

“I was very excited for about three seconds,” she says. Then she realized how onerous it could be to comb through the state archives.

But when her analysis was finished, Dr. Lleras-Muney says, “I was surprised, I was really surprised.” It turned out that life expectancy at age 35 was extended by as much as one and a half years simply by going to school for one extra year.

Her prize-winning paper appeared in Review of Economic Studies. And she ended up with a job as an assistant professor at Princeton. Now, others papers have appeared, examining the effects of changed laws on compulsory education in Sweden, Denmark, England and Wales. In every country, compelling children to spend a longer time in school led to better health.

“You might think that forcing someone to go to school who does not want to be there may not be the same thing as going to school because you want to,” Dr. Lleras-Muney said. “That did not seem to be the case.”

Not everyone was convinced. [...] [I]t might be expected that after a certain point, more years of school would not add to a person’s life span. That, however, is not what the data shows. The education effect never wanes. [...]

Dr. Lleras-Muney and others point to one plausible explanation — as a group, less educated people are less able to plan for the future and to delay gratification. [...] [E]ducation, Dr. Smith at RAND finds, may somehow teach people to delay gratification. For example, he reported that in one large federal study of middle-aged people, those with less education were less able to think ahead.

“Most of adherence is unpleasant,” Dr. Smith says. “You have to be willing to do something that is not pleasant now and you have to stay with it and think about the future.” [...]

An Observation on the Street

In the late 1970’s, Lisa Berkman, now a professor of public policy at the Harvard School of Public Health, took a part-time job at a San Francisco health care center. It drew people from Chinatown and the city’s Italian neighborhood, North Beach, as well as from the Tenderloin district, a poor area where homeless people lived on the streets and mentally ill people roamed. And she noticed something striking.

“In Chinatown and North Beach, there were these tightly bound social networks,” Dr. Berkman recalls. “You saw old people with young people. In the Tenderloin, people were just sort of dumped. People were really isolated and did not have ways of figuring out how to make things work.” [...]

The risks of being socially isolated are “phenomenal,” Dr. Berkman says, associated with twofold to fivefold increases in mortality rates. And the correlations emerged in study after study and in country after country.

Yet, Dr. Berkman adds, there was that perennial question: Did social isolation shorten lives or were people isolated because they were sick and frail and at great risk of death?

She knows that sometimes ill health leads to social isolation. But, Dr. Berkman says, the more she investigated, the more evidence she found that social isolation might also lead to poor health and a shorter life by, for example, increasing stress and making it harder to get assistance when ill. [...]

The cautionary tale, health economists say, is the story of the link between health and wealth.

Over and over again, studies show that health is linked to wealth. It even matters where a person lives.

For example, in a new analysis of Medicare beneficiaries, Stephanie Raymond and Kristen Bronner of Dartmouth College find that the lowest death rates are in the wealthiest places. [...] Race was not a large factor.

“If you control for where people live, the disparities between black and white mortality rates become much smaller,” said Jonathan Skinner, a Dartmouth health economist.

An obvious explanation is that wealth buys health. And it seems plausible. Poorer people, at least in the United States, are less likely to have health insurance or access to medications.

But [Victor Fuchs, a health economist at Stanford] says, then why don’t differences between rich and poor shrink in countries where everyone has health care?

“All you have to do is look at the experience of countries like England that have had health insurance for more than 40 years,” he says. “There is no diminution in the class differentials. It’s been the same in Sweden. It’s true everywhere.”

In fact, Dr. Smith says, the wealth-health connection, at least among adults, goes in the wrong direction. It is not that lower incomes lead to poor health so much as that poor health leads to lower incomes, he found.

A Skewing of the Numbers

Sick people tend to have modest out-of-pocket medical expenses, but often are unable to work or unable to work full time.

The result can be a drastic and precipitous and long-lasting drop in income. As the ranks of middle- and upper-income populations become depleted of people who are ill, there is a skewing of the data so healthy people are disproportionately richer.

That effect emerged when Dr. Smith analyzed data from the National Institute on Aging’s National Health and Retirement Survey, a national sample of 7,600 American households with at least one person aged 51 to 61.

If someone developed cancer, heart disease or lung disease — which will affect about a fifth of people aged 51 to 61 over the next eight years — the household’s income declined by an average of more than $37,000. And its assets — its wealth — fell by $49,000 over the ensuing eight years, even though out-of-pocket medical expenses were just $4,000.

Dr. Smith also asked whether getting richer made people healthier, an effect that could translate into a longer life. It does not, he concluded after studying the large increases in income during the stock market surge of the 1990s. [...]

Income, says Dr. [Samuel Preston, a demographer at the University of Pennsylvania], “is so heavily influenced by health itself.”

Much More Than Genes and Luck

[...] For the most part, genes have little effect on life spans. Controlling heart disease risk factors, like smoking, cholesterol, blood pressure and diabetes, pays off in a more vigorous old age and a longer life. And it seems increasingly likely that education plays a major role in health and life spans.

And then there is the question of what to do. [...] There are just so many questions remaining, says Richard Suzman, a program director at the National Institute on Aging. Even studies showing that, for many people, the die may be cast early in life, do not reveal how best to make changes.

“We have only a vague idea of when and where early experience links to old age or when and where to intervene,” Dr. Suzman says...


Blogger Harry Eagar said...

Maybe school determines whether you get o 60 or not, but once you're at 60, it's grandparents who determine whether you make it to 90 or just 70.

January 05, 2007 2:02 PM  
Anonymous Anonymous said...

It just makes it seem longer.

January 05, 2007 2:41 PM  
Blogger Oroborous said...

One aspect that puzzles me is the assertion that "[t]he education effect never wanes."
What could a 55 year old learn though formal education that would enable her to increase her chances of making it to 60 ?
How many people are capable of learning, if they haven't done so in the previous five decades ?

Maybe it's a statistical fluke.

January 06, 2007 12:43 PM  
Anonymous Anonymous said...

O: I don't think that the line they're drawing is that direct. It's not (just) that education includes lessons about sanitation or fitness. There's some other correlation going on here. (It's easy to see, for example, how being in good enough mental and physical shape to go back to school at 55 would be inversely proportional to dying before turning 60.) In fact, much of the effect seems to be that your chance of dying is much less while in school.

January 07, 2007 9:16 AM  
Blogger Dr. Leonid Gavrilov, Ph.D. said...

Thank you for your interesting post!
Once you have cited the work of Prof. Samuel Preston, perhaps you may find it interesting to take a look at discussion of his book "Fatal Years":
Longevity Science: Fatal Years

April 24, 2007 11:36 AM  

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