Till IL-6 Do Us Part: Elderly caregivers show harmful immune effect

Seniors whose lives revolve around caring for their incapacitated spouses often feel older than their years. It may be more than a feeling, according to a new study.

Over a 6-year period, marital Samaritans caring for a spouse with Alzheimer’s disease or another brain disorder exhibited a dramatic average increase in blood concentrations of a protein involved in immune regulation, concludes a team led by Janice Kiecolt-Glaser and Ronald Glaser, both of Ohio State University in Columbus. During that same time, seniors with healthy spouses displayed a much smaller increase in blood concentrations of the substance, interleukin-6 (IL-6).

As people age, they typically produce IL-6 in larger quantities. Earlier investigations linked particularly high concentrations of IL-6 to heart disease, osteoporosis, arthritis, type 2 diabetes, certain cancers, periodontal disease, and intensified reactions to viral infections (SN: 3/27/99, p. 199).

After an impaired spouse died, IL-6 concentrations in the blood of the former caregiver continued to rise at an elevated rate for as many as 3 years, the researchers report in the July 22 Proceedings of the National Academy of Sciences.

“In older caregivers, it may be that their immune system activity gets reset to a higher [and unhealthy] level and stays there for several years after a spouse’s death,” says Glaser.

To discern the IL-6 trends, the researchers obtained at least two blood samples annually from 119 caregivers and from 106 people with healthy spouses or who were widowed, separated, divorced, or never married. Participants, a majority of whom were women, ranged in age from 55 to 89. Shortly before the study began, 28 of the caregivers’ spouses had died. Another 50 of them died in the ensuing 6 years.

The researchers found that caregivers’ average IL-6 concentrations in blood increased at four times the rate observed in noncaregivers. Depression, loneliness, and feelings of uncontrollable stress reported by the study participants couldn’t account for the changes, the researchers note.

“Caregivers for impaired spouses experience a kind of distress that isn’t easily measured,” Kiecolt-Glaser says.

The investigators now plan to monitor the caregivers’ health over the next 4 to 5 years. In a 1990 study directed by psychologist Richard Schulz of the University of Pittsburgh, elderly people tending spouses with a spectrum of ills died at a markedly greater rate than other seniors did.

For now, the new data raise hopes that future treatments designed to reduce excess amounts of IL-6 could prove beneficial for caregiving seniors, says Glaser.

“The discovery of age-related increases in IL-6 isn’t just about the effect of caregiving,” comments epidemiologist Burton H. Singer of Princeton University. “It’s about the effect of experiencing chronic adversity.”

If that’s true, it raises the stakes for finding ways to relieve the most unrelenting forms of adversity. For instance, Singer theorizes, if a woman who cares for a husband with Alzheimer’s disease also supports two children on a minimum wage, she may be at particularly high risk for developing a life-threatening illness.

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Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.

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