News Release

Stress: It's Not Just All In Your Head; Scientists Map The Wear And Tear Of Daily Life

Peer-Reviewed Publication

Center for Advancing Health

Researchers have finally proven that feeling "stressed out" isn't just something in our heads, it also shows up in our bodies - and it can have deadly consequences.

In a paper published in the January 15 issue of the New England Journal of Medicine, Bruce S. McEwen, PhD, of Rockefeller University, identifies eight physical indicators in the body - from blood pressure to cortisol levels to abdominal fat- that can be measured to give a tangible indication of an individual's personal stress load.

McEwen introduces the concept of what he and his colleagues have labeled "allostatic load," which is the price our bodies pay for the ability to adapt to stress. "From the standpoint of health," says McEwen, "what is even more important than how we feel about the stressful events in our lives is how our bodies react in terms of the stress hormones they produce."

Stressful life events - whether the loss of a loved one, divorce or job loss - as well as the daily wear and tear of living, such as traffic jams and family disagreements, set off the release of stress hormones that help our bodies charge up to meet the challenge.

"During episodes of acute stress, stress hormones provide a protective function by activating the body's defenses," says McEwen, "but when these same protective hormones are produced repeatedly, or in excess, because of chronic stress, they create a gradual and steady cascade of harmful physiological changes."

Higher levels of allostatic load can lead to suppression of the immune system (which leaves us open to infection and infectious diseases), as well as bone loss, muscular weakening, atherosclerosis and increased insulin levels that cause higher levels of fat deposition in the body, especially around the abdomen.

"People end up with that 'apple' body shape that researchers have shown over and over again predisposes us to heart disease," says McEwen.

Even the brain can be affected. "In fact," says McEwen, "results from studies on aging animals and humans suggest that a lifelong allostatic load may accelerate changes in the brain that can lead to memory loss."

McEwen and his colleagues followed a group of successfully aging elderly people for three years using common tests to measure, for example, blood pressure, blood glucose levels and cortisol and cholesterol levels to determine how their allostatic load levels affected their health. They found that those with the highest allostatic loads were most likely to develop newly diagnosed cardiovascular disease and significantly more likely to show declines in mental and physical functioning.

The best antidote to break the cycle, McEwen says, is the simplest: exercise. "Of all the things we can do to lower stress levels and counteract allostatic load," says McEwen, "exercise seems to be the most effective, along with a prudent diet. Exercise breaks insulin resistance and often helps to end the vicious cycles of stress-eating, over-indulging in alcohol , cigarette smoking and other unhealthy habits."

But McEwen's advice comes with a caveat: exercise won't help everyone without also dealing with other factors in their lives. "Numerous studies show that the lower down you are on the socioeconomic scale, the poorer your health. This is largely independent of access to health care or lack of health insurance." According to McEwen, the stress of living in poverty, or working in a low-level job that lacks autonomy, or residing in an unhealthy, polluted environment has an enormous impact on health status that researchers are only just beginning to understand.

The research was funded by the John D. and Catherine T. MacArthur Foundation as part of its Research Network on Socioeconomic Status and Health.

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