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 ampl
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Ohio State University