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Study of
Elderly
Long-Term Stress Appears To Damage
Caregivers Immune Systems
June 30, 2003 - Older people who take
care of chronically ill loved ones over long periods experience
continuing stress that boosts the risk of age-related diseases by
prematurely aging caregivers' immune systems, according to a new
study.
Levels of a damaging compound known as a
proinflammatory cytokine not only increased considerably faster among
those taking care of ailing spouses but also continued to increase
faster for years after the spouses died.
Authors are Drs. Janice K. Kiecolt-Glaser,
Cathie Atkinson, William B. Malarkey and Ronald Glaser of Ohio State's
College of Medicine and Drs. Robert C. MacCallum and Kristopher J.
Preacher of UNC's department of psychology, College of Arts and
Sciences.
"Our study examined effects of a
long-term chronic stress situation on overproduction of the cytokine
IL-6 in older adults," said MacCallum, director of the L.L. Thurstone
Psychometric Laboratory at UNC. "IL-6 is a substance secreted by a
variety of cells in the body, including blood cells and bone marrow.
Among other things, it is associated with the functioning of the
immune system in its response to challenges, as well as the
inflammatory response to injury and infection."
As people age, production of IL-6 tends
to increase, he said. Overproduction of IL-6 has been linked to a
variety of age-related conditions, including cardiovascular disease,
arthritis, periodontal disease, frailty and diabetes.
The study involved examining IL-6 levels
in two groups of older adults over six years. One group of 119 people
consisted of men and women who were caring for a spouse with dementia,
usually Alzheimer's disease. The other group consisted of 106 people
who were not caregivers. When they entered the investigation,
subjects' average age was 70.5 years.
"Statistical analyses showed a more
rapid increase in IL-6 level for the caregiver group than for the
non-caregiver group, such that the average rate of increase was about
four times greater in the caregiver group," MacCallum said.
The team carried out additional analyses
to learn whether the difference might be associated with other
variables such as age, gender, ethnicity, depression, loneliness or
health-related behaviors including smoking, exercise and sleep
patterns.
"We found no other variables that
accounted for the group difference in rate of change in IL-6,"
MacCallum said.
Before and during the study, some of the
spouses of the caregivers died, he said. Further analyses compared
levels of the proinflammatory cytokine in former caregivers and those
who continued taking care of their loved ones. Results showed no
significant difference in rate of change in IL-6 between the two
groups, indicating that the negative impact of caregiving may last
long after the ill spouse has died.
"Overall, the study provides evidence
that a severe chronic stress situation can accelerate production of
IL-6, a phenomenon which has been shown to be associated with the
onset and course of a variety of age-related diseases and conditions,"
MacCallum said. "In effect, this phenomenon represents a sort of
premature aging of the immune response."
A report on the research, conducted by
scientists at Ohio State University and the University of North
Carolina at Chapel Hill, will appear online Monday afternoon (June 30)
in the Proceedings of the National Academy of Sciences. |
