[I think it was only this Fall Doug was remarking that there was a paucity of research on this subject. But now there seems to be an explosion, at least in the professional journals. And their conclusions are remarkably strong compared to what went before according to this NYT survey.]
Michael
For Good Health, It Helps to Be Rich and Important
By ERICA GOODE
D octors usually evaluate patients' vulnerability to serious
disease by inquiring about risk factors like cigarette smoking,
obesity, hypertension and high cholesterol.
But they might be better off asking how much money those patients
make, how many years they spent in school and where they stand
relative to others in their offices and communities.
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Trying to explain why illness diminishes with a rise in social class.
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Scientists have known for decades that poverty translates into
higher rates of illness and mortality. But an explosion of research
is demonstrating that social class -- as measured not just by
income but also by education and other markers of relative status
-- is one of the most powerful predictors of health, more powerful
than genetics, exposure to carcinogens, even smoking.
What matters is not simply whether a person is rich or poor,
college educated or not. Rather, risk for a wide variety of
illnesses, including cardiovascular disease, diabetes, arthritis,
infant mortality, many infectious diseases and some types of
cancer, varies with relative wealth or poverty: the higher the rung
on the socioeconomic ladder, the lower the risk. And this
relationship holds even at the upper reaches of society, where it
might seem that an abundance of resources would even things out.
Social class is an uncomfortable subject for many Americans. "I
think there has been a resistance to thinking about social
stratification in our society," said Dr. Nancy Adler, professor of
medical psychology at the University of California at San Francisco
and director of the John T. and Catherine D. MacArthur Foundation
Research Network on Socioeconomic Status and Health. Instead,
researchers traditionally have focused on health differences
between rich and poor, or blacks and whites (unaware, in many
cases, that race often served as a proxy for socioeconomic status,
since blacks are disproportionately represented in lower income
brackets).
But the notion that a mid-level executive with a three-bedroom,
split-level in Scarsdale might somehow be more vulnerable to
illness than his boss in the five-bedroom colonial a few blocks
away seems to have finally captured scientists' attention.
In the past five years, 193 papers addressing aspects of
socioeconomic status and health have appeared in scientific
journals -- twice the number in the previous five-year period. The
National Institutes of Health last year declared research on
disparities in health related to social class or minority status
one of its highest priorities, said Dr. Norman Anderson, associate
director of the N.I.H. And a recent conference in Bethesda, Md., on
the topic, sponsored by the New York Academy of Sciences and the
MacArthur Foundation network, drew more than 250 participants from
a wide variety of disciplines.
Executive Privilege Includes Longevity
A study following 18,133 male civil servants over 25 years shows that
the grade of employment was a strong predictor of mortality,
especially before retirement.
[060199hth-socioeconomic-status.1.gif]
The New York Times
Source: M. G. Marmot and Martin J. Shipley.
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What first compelled researchers interest was a now-classic study,
begun in the late 1960's, of men in the British civil service. The
Whitehall study, directed by Dr. Michael Marmot, director of the
International Center for Health and Society at University College
London, tracked mortality rates over 10 years for 17,530 male civil
service employees.
When the data were analyzed, the researchers were astonished to
discover that mortality rates varied continuously and precisely
with the men's civil service grade: the higher the classification,
the lower the rates of death, regardless of cause.
This finding was as perplexing as it was intriguing. The men all
had jobs, and equal access to health care under Britain's national
health system. But mortality rates for men in the lowest civil
service classification, the researchers found, were three times
higher than those for men in the highest grade. And a 25-year
follow-up of the Whitehall subjects, some results of which were
published in 1996, found the social class gradient persisted well
past retirement, even among men into their late 80's.
Subsequent studies demonstrated a similar relationship between
socioeconomic status and mortality in the United States and Canada.
What could account for such startling findings? One plausible
explanation was that lower-ranked men might engage in more risky
behaviors, like smoking.
But the same health disparity from pay grade to pay grade that was
evident in smokers held for nonsmokers, too. And all coronary risk
factors combined, the researchers found, accounted for only a third
of the differences between grades.
Stress, or other aspects of psychological life that can have an
impact on a person's vulnerability to disease, the Whitehall group
reasoned, might also play a role in the results. Prolonged exposure
to stress, researchers have found, can lead to abnormalities in
immune function and glucose metabolism, and destroy brain cells
involved in memory. And studies show that the lower one's social
status, the more stressed people feel, and the more stressful
events they encounter in their lives.
Dr. Sheldon Cohen, professor of psychology at Carnegie Mellon
University in Pittsburgh, has demonstrated a link between social
status and vulnerability to infectious disease in male macaque
monkeys. In a study carried out in conjunction with primate
researchers at Wake Forest University School of Medicine, Dr. Cohen
found that males at the lower end of the dominance hierarchy were
more susceptible to a cold virus than dominant males.
Dr. Cohen and his colleagues at Carnegie Mellon then replicated
those findings in humans. Subjects in the study were asked to rate
their relative standing in their community on a social status
ladder, then were exposed to mild respiratory virus. People who
ranked themselves low on the ladder were more likely to become
infected with the virus than those who ranked themselves higher up
on the ladder.
In another study, the researchers found that people who had been
unemployed for one month or more under highly stressful conditions
were 3.8 times more susceptible to a virus than people who were not
experiencing a significant stressful situation.
At least in primates, the interaction of stress with social class
and illness, however, depends both on the nature of the stress and
the context in which it occurs, as demonstrated in a series of
studies by Dr. Jay R. Kaplan, a professor of pathology and
anthropology at Wake Forest.
In a crowded situation where resources are scarce, for example,
male monkeys at the lowest end of the dominance hierarchy, who must
scramble hardest to survive, are likely to feel the most stress.
And in studies of primates in the wild, researchers find that
subordinate animals show higher levels of stress hormones.
But when Dr. Kaplan and his colleagues fed male monkeys a "luxury"
diet, high in fat and cholesterol, and moved them each month for
two years into a new group of strange males, it was the dominant
animals, forced to reassert their position continually, who
suffered the most stress. Under such conditions, Dr. Kaplan finds,
dominant males show a hypervigilant response, and have higher rates
of coronary artery disease than subordinates.
For humans and primates, a sense of control over life events is
intimately related to stress. And control seems to have been one
factor at work in the Whitehall study.
In 1985, Dr. Marmot and his colleagues launched Whitehall II, a
second large-scale study, which included civil servants of both
sexes and which collected more detailed information on the
participants.
As part of the study, employees were asked to rate the amount of
control they felt over their jobs. Managers also rated the amount
of control employees had. Job control, the researchers found,
varied inversely with employment grade: the higher the grade, the
more control. And the less control employees had, as defined either
by their own or managers' ratings, the higher the employees' risk
of developing coronary disease. Job control, in fact, accounted for
about half the gradient in deaths from pay grade to pay grade.
To some extent, people's ability to withstand stress, and the ways
in which they interpret and respond to life events, are shaped by
early life, the product of what one social scientist, Dr. Clyde
Hertzman of the University of British Columbia, calls "the long arm
of childhood." Genetics play a role, as does nutrition. (In the
Whitehall study, height -- which varies with social class -- was
used as a rough indicator of childhood influences on development,
and accounted for a small portion of the association between
mortality and employment grade.) And scientists have found that
early life experiences -- abuse and neglect, for example -- can
alter brain development and influence responses to stressful
events.
Any discussion of socioeconomic status in the United States of
necessity involves a discussion of race, since the two are entwined
in complex, sometimes inextricable, ways. Proportionally, far more
African-Americans live in poverty than whites: 28.4 percent of
blacks fell below the poverty line in 1996, compared with 11.2
percent of whites, according to Government data.
Death rates for African-Americans from all causes are 1.6 times
higher than for white Americans, Dr. David R. Williams of the
University of Michigan's Institute for Social Research, said at the
Bethesda conference.
Life expectancy for blacks and whites also varies. At age 45, a
white man can expect to live five years longer than an
African-American man, and white women can expect to live 3.7 years
longer than their black counterparts.
If socioeconomic status is taken into account, health differences
between blacks and whites decrease substantially: Black men in the
highest income brackets, for example, have a life expectancy 7.4
years longer than black men in the lowest brackets, Dr. Williams
said. White men at top income levels live 6.6 years longer than
their lowest-income counterparts.
But race and to some extent sex still have an impact on health that
is independent of social class. The gap in infant mortality rates
between blacks and whites, for example, actually increases with
higher social status. And being black or female discounts some of
the advantages afforded by education: white men accrue health
advantages with every additional year of schooling they receive.
But black men and women, though they also show gains, show them
only through high school, according to an analysis of Federal data
by Dr. Adler and Dr. Burton Singer of Princeton University's Office
of Population Research. White women, the researchers found,
continue to gain in health status through college, but unlike white
men, do not receive the gains in health bestowed by post-graduate
education.
Social exclusion, residential segregation and other expressions of
institutional racism magnify the impact of socioeconomic status.
Several studies, for example, have shown higher adult and infant
mortality rates for people living in segregated areas.
For both blacks and whites, living in a neighborhood where social
bonds have eroded may have negative effects on health. Dr. Robert
Putnam of Harvard University coined the term "social capital" to
describe the elements that contribute to social cohesion.
Dr. Ichiro Kawachi, director of the Harvard Center for Society and
Health, has explored one aspect of social capital -- interpersonal
trust -- and its relationship to national and community rates of
illness and death.
Dr. Kawachi and his colleagues correlated mortality rates in states
with the percentage of state residents who agreed with the
statement, "Most people would try to take advantage of you if they
got the chance." Death rates, Dr. Kawachi reported at the Bethesda
conference, were strongly linked to level of social trust, with the
most mistrustful ratings clustering in southern and northeastern
states. Another study, of Chicago neighborhoods, yielded similar
findings: neighborhoods in which more residents agreed with the
statement "Neighbors can be trusted" had lower mortality rates.
Why are neighborhoods or states with higher levels of trust
healthier? Dr. Kawachi suggests that in neighborhoods where social
trust is high, negative health behaviors -- smoking and alcohol
consumption, for example -- might be discouraged through community
pressure.
Residents in high trust neighborhoods may also share more
resources, be more willing to help one another out and offer one
another more emotional support. "It is speculation," Dr. Kawachi
said, "but probably these little things add up to quite important
health differences."
Even so, the relationship between social class and health is
unlikely to be entirely explained by social capital, or by any
other single dimension of life experience. Said Dr. Adler, "There
isn't going to be a single explanation or an easy solution, but
we've started mapping out some of the places where we can
intervene."
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Copyright 1999 The New York Times Company