The New Age
Michael Stravato for The New York Times
Irma
Lara, 75, who came to the
By GINA KOLATA
Published: January 3, 2007
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
He
is venturing, of course, into one of the prevailing mysteries of aging, the
persistent differences seen in the life spans of large groups. In every
country, there is an average life span for the nation as a whole and there are
average life spans for different subsets, based on race, geography, education
and even churchgoing.
But
the questions for researchers like Dr. Smith are why? And what really matters?
The
answers, he and others say, have been a surprise. 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: “Giving people more Social Security income, or less for that
matter, will not really affect people’s health. It is a good thing to do for
other reasons but not for health.”
Health
insurance, too, he says, “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. And there is
evidence that people with more powerful jobs and, presumably, with more control
over their work lives, are healthier and longer lived.
But there is little dispute about the primacy of
education.
“If
you were to ask me what affects health and longevity,” says Michael Grossman, a
health economist at the City University
of New York, “I would put education at the top of my list.”
Graduate Student Finds Answer
The
first rigorous effort to decide whether education really changes people so they
live longer began in a most inauspicious way.
It
was 1999 and 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
“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.
Victor
Fuchs, a health economist at Stanford, points out that it is not clear how or
why education would lead to a longer life.
And,
he said, there are other mysteries. For example, women increased their years of
schooling more than men have in recent decades. But men are catching up with
women in their life spans.
And
it 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. But most researchers say they are swayed by Dr. Lleras-Muney’s work and the studies in other countries.
That, though, leaves the question of why the education effect occurs.
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. If true, that may, for example, explain the
differences in smoking rates between more educated people and less educated
ones.
Smokers
are at least twice as likely to die at any age as people who never smoked, says
Samuel Preston, a demographer at the University of
Pennsylvania. And not only are poorly educated people more likely to
smoke but, he says, “everybody knows that smoking can be deadly,” and that
includes the poorly educated.
But
education, Dr. Smith at
“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.”
He
deplores the dictums to live in the moment or to live for today. That advice,
Dr. Smith says, is “the worst thing for your health.”
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
“In
Chinatown and
A
few years later, she was haunted by that observation. She had entered graduate
school and was studying Seventh-day Adventists when she began to wonder whether
the standard explanation for their longer lives — a healthy, vegetarian diet —
was enough.
“They
were at decreased risk from many, many diseases, even ones where diet was not
implicated,” Dr. Berkman says. And, she adds, “it seemed they simply had a slower rate of aging.”
Seventh-day
Adventists, like the people in Chinatown and
Thirty
years later, studies have borne out her hunch.
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.
This is
last of four articles looking at the science of aging. The articles will remain
online at nytimes.com/aging.
But
researchers also warn that their findings that education and, to a lesser
degree, social networks, may directly affect health do not necessarily mean
that other hypotheses would also hold up. 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. So in
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
An
obvious explanation is that wealth buys health. And it seems plausible. Poorer
people, at least in the
But
Dr. Fuchs 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
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.
“I
find almost no role of financial anything in the onset of disease,” Dr. Smith
says. “That’s an almost throw-you-out-of-the-room thing,” he confesses, but the
data, he and other economists insist, is consistent.
Income,
says Dr. Preston, “is so heavily influenced by health itself.”
Much More Than Genes and Luck
As
director of the National Institute on Aging, Dr. Hodes
often speaks to policy makers, giving briefings on the latest scientific
findings. But, he and others say, all too often there is a
disconnect.
There
are some important findings: Health and nutrition early in life, even prenatally, can affect health in middle and old age and can
affect how long people live.
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. It might seem logical to act now,
pouring money into education or child health, for example.
But
scientists often say they would like good evidence beforehand that a program
that sounds like it would make a difference, like keeping students in school
longer, really works. And if the goal is longer and healthier lives, is that
the most cost-effective way to spend public money?
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.
“When
it comes to changing things,” says Dr. Skinner, the