Chronic stress steals years from caregivers

The chronic stress that spouses and children develop while caring for Alzheimer's disease patients may shorten the caregivers' lives by as much as four to eight years, suggests a study from Ohio State University, Columbus. The research provides concrete evidence that the effects of chronic stress can be seen at the genetic and molecular level in chronic caregivers' bodies.

Earlier research had shown that mothers caring for chronically ill children developed alterations in their chromosomes that effectively amounted to several years of additional aging among those caregivers. However, that work looked only at a broad community of immune cells without identifying the specific components responsible for the changes.

The OSU team, along with the National Institute on Aging, Bethesda, Md., wanted to identify the exact cells involved in the alterations, as well as the mechanisms that caused them. They focused on telomeres, areas of genetic material on the ends of a cell's chromosomes. Over time, as a cell divides, those telomeres shorten, losing genetic instructions. An enzyme--telomerase--normally works to repair that damage to the chromosome.

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"Telomeres are like caps on the chromosome," explains Ronald Glaser, professor of molecular virology, immunology and medical genetics and head of the Institute for Behavioral Medicine Research. "Think of it as a frayed rope--if the caps weren't there, the rope would unravel. The telomeres insulate and protect the ends of the chromosomes. As we get older, the telomeres shorten and the activity of the telomerase enzyme lessens. It's part of the aging process."

For the study, the researchers turned to a population of Alzheimer's disease caregivers they had worked with before and compared them with an equal number of noncaregivers matched for age, sex, and other aspects. They analyzed blood samples from each group, looking for differences in the telomeres and the enzyme, as well as populations of immune cells.

"Caregivers showed the same kind of patterns present in the study of mothers of chronically ill kids," Glaser relates, adding that these alterations amount to a shortened lifespan of four to eight years. "We believe that the changes in these immune cells represent the whole cell population in the body, suggesting that all the body's cells have aged that same amount."

The caregivers also differed dramatically with the control group on psychological surveys intended to measure depression, a clear cause of stress. "Those symptoms of depression in caregivers were twice as severe as those apparent among the control group," points out Jan Kiecolt-Glaser, professor of psychology and psychiatry. "Caregivers also had fewer lymphocytes, a very important component of the immune system. They also displayed a higher level of cytokines, molecules key to the inflammation response, than did the control group."

Other experiments demonstrated that the actual telomeres in blood cells of caregivers were shorter than those of the controls, and that the level of telomerase repair enzyme among caregivers was lower. Kiecolt-Glaser indicates that there is ample epidemiological data illustrating that stressed caregivers die sooner than people not in that role. "Now we have a good biological reason for why this is the case. We now have a mechanistic progression that shows why, in fact, stress is bad for you, how it gets into the body, and how it gets translated into bad biological outcome."

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COPYRIGHT 2008 Gale, Cengage Learning