Last Updated: 2003-06-30 17:00:18 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Research has indicated that chronic stress can take a hefty toll on a person's health, and a new study offers one potential reason why.

Investigators found that older people under chronic stress had higher-than-normal elevations of interleukin-6 (IL-6), an immune-system protein in the blood that promotes inflammation. IL-6 has been linked with various age-related conditions such as heart disease, diabetes, osteoporosis, frailty and certain cancers.

"This is how chronic stress can really affect health," said study author Dr. Janice K. Kiecolt-Glaser, a professor of psychiatry at Ohio State University in Columbus.

"The take-home advice from this study is that it's really important to try to deal with stress," she told Reuters Health. "The older you are, the more it really matters."

Over the course of the six-year study, IL-6 levels increased an average of four times faster among men and women who were caring for spouses with dementia than among people who were not caring for ill spouses. The study participants ranged in age from 55 to 89 at the beginning of the study, with an average age of 71.

The 119 caregivers reported spending about 10 hours a day on average caring for a spouse when the study began, Kiecolt-Glaser and colleagues note in the online early edition of the Proceedings of the National Academy of Sciences.

Tests conducted periodically throughout the study period showed that the caregivers experienced consistently higher levels of stress and loneliness than the 106 non-caregivers.

In the cases where spouses died during the study, caregivers continued to have high IL-6 levels, even several years later.

All of the study participants were healthy at the outset of the study, and the caregiving and non-caregiving groups had similar levels of chronic health problems during the follow-up period.

However, it's likely that the caregivers would go on to develop a greater number of illnesses due to their higher IL-6 levels, Kiecolt-Glaser said.

"These data provide important evidence of a key mechanism through which chronic stressors may have potent health consequences for older adults, accelerating risk of a host of age-related diseases," the researchers conclude in their paper.