Horacio Cardo

If you want to get a sense of how social status affects health, then take a ride on Washington's metro system. Start in the blighted southeast section of downtown. For every mile traveled to tony Montgomery County in Maryland, life expectancy rises about a year and a half. By the time you get off, says Sir Michael Marmot, a British epidemiologist who has been studying the link between social position and health, you will find a "20-year gap between poor blacks at one end of the journey and rich whites at the other."

The notion that status in and of itself — not just as a stand-in for money, education or nutrition, quality of medical care, bad habits or good genes — largely determines how healthy you are has become a cutting edge of public health research. Biologists, neurologists, economists, psychologists, primatologists and more have been trying to pinpoint precisely what links the two. "The whole issue of health disparities is very hot now," said Nancy Adler, a professor of medical psychology at the University of California, San Francisco. "There is a meeting every other minute."

This summer, Sir Michael, a leader in the field, is publishing his first book for the general public, in which he pulls together 25 years of research, declaring that status is more important than genetics, supersize fast food or even smoking.

But figuring out that status matters is one thing; figuring out why is another. How does status get under the skin?

There are now tens of thousands of papers and research projects offering theories. But the answers are as tantalizing, and controversial, as they are elusive.

After all, why should the ability to get a reservation tonight at the exclusive Per Se restaurant instead of Red Lobster or playing golf at Augusta instead of Van Cortlandt Park prolong one's life? Why, as Sir Michael writes in "The Status Syndrome: How Social Standing Affects Our Health and Longevity" (Times Books), "should educated people with good stable jobs have a higher risk of dropping dead than people with a bit more education or slightly higher status jobs? Is living in a five-bedroom house with three bathrooms better for your health than `crowding' the spouse and two children into a four-bedroom house with only two?"

The answer, Sir Michael said in an interview from London, lies in the psychological effects of inequality: "Your position in the hierarchy very much relates to how much control you have over your life and your opportunities for full social engagement." Those feelings, he and others argue, profoundly affect one's health.

What transformed the health establishment's thinking about the link between status and health was the Whitehall Studies, long-term research projects that have tracked the health of thousands of British civil servants since 1967. Whitehall provides something pretty close to an ideal real-world laboratory. After all, it is not the gap between the haves and have-nots where one might find the most compelling evidence for the status syndrome, but between the have-a-lots and the have-the-mosts. Civil servants all have office jobs, health care and high job security, but they are sharply classified according to rank.

What researchers found is that those in the lowest grade were three times more likely to die at any given age as those in the highest. One explanation might be that people on the lowest rung have unhealthier habits — smoking, not exercising, bulking up on fast food. But researchers who looked more closely at coronary heart disease concluded that risk factors accounted for only one-third of the differences between those at the top of the social hierarchy and those at the bottom. "A smoker who is low employment grade has a higher risk of heart disease than a smoker who is higher grade," writes Sir Michael, the former director of the

Whitehall study. "A nonsmoker who is lower grade has a higher risk of heart disease than a nonsmoker who is higher grade."

Whitehall shook the public health establishment. "Those findings caused me to change my career," said Ms. Adler, referring to results published in the early 90's. "It was so dramatic and so puzzling." Still, researchers in the United States were slow to focus on the subject in earnest, she added, probably because of America's preoccupation with race and ethnicity as opposed to class.

Ms. Adler, who directs the John D. and Catherine T. MacArthur Foundation Research Network on Socioeconomic Status and Health, has been looking at how people's own perception of their status affects their health. She found, for instance, that among white women who shared the same socioeconomic level, those who viewed themselves as occupying a higher social rung were in better health than those who did not.

Many researchers argue the reason for such results is stress. "Sustained, chronic and long-term stress is linked to low control over life circumstances," Sir Michael writes, and low control is related to social position.

Stress triggers a higher heart rate, a release of adrenaline, glucose and other neurological responses to help the body respond to a short-term threat. But when extended over long periods of time, they can harm the cardiovascular and immune systems, making individuals more vulnerable to a wide range of conditions including infections, diabetes, high blood pressure, heart attack, stroke, asthma and aggression.

Of course, being at the top can be extremely stressful if the hierarchy is unstable. As Robert M. Sapolsky, a professor of biology and neurology at Stanford University, has shown in his groundbreaking work with primates, dominant baboons have much lower rates of stress-related disease — unless they have to fight to maintain their position as the leader of the pack. Then, they have the worst physiology (differences that certainly could not be due to, say, different educational levels or a pack-a-day habit.) As Dr. Sapolsky has said: "I would not have wanted to have been the czar of Russia in the winter of 1917. You don't want to be on top of a hierarchy if everybody's trying to burn down the castle."

That's why Sir Michael explains that status "is partly related to how you see yourself and how others see you, but it is also related to our set of social arrangements," or how a particular community accentuates or buffers differences in social position.

Perhaps as important as stress, though, is a network of social support — friends, family and community. Some epidemiologists have done research showing that a strong social network can actually increase someone's resistance to disease. One study has found a connection between life expectancy and a high level of participation in voluntary organizations. Married men and women consistently have lower mortality than singles, even aside from lifestyle differences, said Sir Michael, evidence that perhaps Adelaide was right to lament in "Guys and Dolls" that "just from waiting around for that plain little band of gold, a person can develop a cold."

Critics have a different lament. Economists in particular are extremely skeptical that anything besides money and education — and the material advantages and lifestyle they bring — are at work. Angus Deaton, a professor of economics and international relations at Princeton, who says he is probably more sympathetic to the argument than many of his colleagues, still thinks the supposed links between prestige and health are fuzzy. "I'm sure there's some effect of social status. But I don't know how strong it is."

"How would we know what the effect of social status was," he asks, "having parceled out all these other things," like education, employment, income and so on? The studies don't take account of differences in childhood experiences, for example, he said.

How would one explain what is known as the "Hispanic paradox," the fact that Hispanics have lower than average rates of chronic illness than whites in the United States even though many live in relatively poorer social and economic conditions? "There has been no real attempt to control for all of those things at the same time," he said.

It may be, Mr. Deaton suggests, that health affects social status more than the reverse. "The major reason that people retire from the work force is that they're sick, he said. "If you get sick in America, it does terrible things to your social status."

Even advocates concede disentangling causes is tricky. Donald Redelmeier, a professor of medicine at the University of Toronto, explains that higher status could mean that other people who have an investment in maintaining your reputation — an agent or a personal trainer and nutritionist — help enforce a healthier regime. Think of it as the entourage effect.

Dr. Redelmeier and a colleague analyzed the lifespans of actors who won Oscars, their co-stars and the losing nominees — 1,649 performers in all. They found that winning an Oscar added nearly four years to actors' life spans. If that figure doesn't sound overly impressive, consider that completely eliminating all kinds of cancer in North America would add only about three and a half years to life expectancy, Dr. Redelmeier said when the study was first published two years ago.

Maybe it is purely the prestige or maybe the Oscar effect is a result of peace of mind. "When a critic gives you a nasty review, it doesn't stick," Dr. Redelmeier suggested, because "you have that statuette, an uncontestable marker of peer approval."

Certainly, people deeply value status. Ask yourself which scenario you would prefer: an income of $125,000 when the average of those around you is $100,000; or an income of $175,000 when those around you is $200,000. Most people surveyed chose the $125,000 — a higher relative status — even though they would be worse off in absolute terms.

That's been the case for a long time, says Robert Evans, an economist at the University of British Columbia who has studied the link between status and health. Even Julius Caesar remarked, "I would rather be first in a little Iberian village than second in Rome."

The New York Times Company. Reprinted from The New York Times, Arts & Ideas, of Saturday, May 15, 2004.