Civil servants' divided health

The health gap between social classes could in part result from differences in psychological well-being, according to a leading epidemiologist.

Psychological factors may cause physical changes that add to health problems already present from poor diet, for example, according to Michael Marmot, director of the international centre for health and society at University College, London.

Professor Marmot has been working on Whitehall II, a study of thousands of British civil servants. It and Whitehall I have shown that men and women in the lower social ranks are three times as likely to die in a given time period as those at the top.

"None of the men or women in the Whitehall studies are poor by any absolute standard," says Professor Marmot.

Stress in itself does not cause ill-health. But if it goes hand-in-hand with a lack of control over what is happening then it does cause increased ill-health.

Professor Marmot says psycho-social factors, such as lack of control in the workplace or lack of family support, could influence health-related habits and thus be indirectly affecting health. They could also be influencing health directly, "by a mechanism yet to be uncovered".

The scientists have found that people in the upper grades have high levels of high-density cholesterol, which is associated with a lower heart disease risk. Those in the lower grades had high levels of low-density cholesterol, which is connected with higher heart disease risk. Overall cholesterol levels in both groups are the same.

These cholesterol levels may be caused by insulin resistance, which has been discovered to be more common in the lower grades. There are many possible causes of insulin resistance, including psycho-social factors, says Professor Marmot. "A disorder in insulin resistance could be playing a significant role in enforcing and reinforcing social variations in health," he says. "Research must now investigate what causes insulin resistance."