Ohio State University
Chronic stress can steal years from caregivers' lifetimes

http://www.eurekalert.org/pub_releases/2007-09/osu-csc091807.php

COLUMBUS , Ohio – 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, a new study suggests.

The research also provides concrete evidence that the effects of chronic
stress can be seen both at the genetic and molecular level in chronic
caregivers' bodies.

The findings, reported this month by researchers from Ohio State
University and the federal National Institute of Aging, were published
in the Journal of Immunology.

These are the latest results from a nearly three-decade-long program at
Ohio State investigating the links between psychological stress and a
weakened immune status. Previous studies have examined medical students,
newlyweds, divorced spouses, widows, widowers and long-married couples,
in each case, looking for physiological effects caused by psychological
stress.

In their recent study, Ronald Glaser, a professor of molecular virology,
immunology and medical genetics, and Jan Kiecolt-Glaser, a professor of
psychology and psychiatry, teamed with Nan-ping Weng and his research
group from the National Institute of Aging.

Earlier work by other researchers had shown that mothers caring for
chronically ill children developed changes in their chromosomes that
effectively amounted to several years of additional aging among those
caregivers.

That work, remarkable as it was, looked only at a broad community of
immune cells without identifying the specific immune components
responsible for the changes. The Ohio State-NIA team wanted to identify
the exact cells involved in the changes, 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, Glaser said.

“Telomeres are like caps on the chromosome,” said Glaser, head of Ohio
State 's 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,” he said. “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 non-caregivers matched for age, gender and other
aspects. They analyzed blood samples from each group, looking for
differences in both 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 said, adding that the changes
the Ohio State/NIA team saw amounted 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,” Kiecolt-Glaser said.

“Caregivers also had fewer lymphocytes,” Glaser said, “a very important
component of the immune system. They also showed a higher level of
cytokines, molecules key to the inflammation response, than did the
control group.”

Other experiments showed that the actual telomeres in blood cells of
caregivers were shorter than those of the controls, and that the level
of the telomerase repair enzyme among caregivers was also lower.

Kiecolt-Glaser said that there is ample epidemiological data showing
that stressed caregivers die sooner than people not in that role.

“Now we have a good biological reason for why this is the case,” she
said. “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 a bad biological outcome.”

Much of the Ohio State work is now shifting to studies on how to
intervene with that stress in hopes of slowing the weakening of the
immune system in highly stressed people.

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This research was supported in part by both the National Institute of
Aging and the National Institutes of Health. David Beversdorf and Bryon
Laskowski, both at Ohio State, and Amanda Damjanovic, Yinhua Yang, Huy
Nguyen and Yixiao Zou, all with the National Institute of Aging, worked
on this study.