Alzheimer's caregivers' cells seen to age faster

Tue Sep 25, 11:40 AM ET
The stress of taking care of someone with Alzheimer's may cut a person's life short, judging by the effect seen on the genetic material in their cells.
Researchers found that caregivers of Alzheimer's patients had a shortening of the telomeres, the genetic material at the end of chromosomes that promotes error-free cell division. Telomeres gradually shorten over time, and the effect seen in this study was equivalent to four to eight years of aging, Dr. Nan-ping Weng of the National Institute on Aging in Baltimore and colleagues report.
The changes were seen in immune cells known as peripheral blood mononuclear cells (PBMCs), but "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," Dr. Janice K. Kiecolt-Glaser of The Ohio State University in Columbus, one of the study's authors, said in a press release accompanying the study.
To better understand how this stress affects both immunity and aging, the researchers looked at 41 people caring for loved ones with Alzheimer's disease and 41 individuals matched by age who weren't caring for an ill person. Caregivers had been looking after the Alzheimer's patients for an average of five years.
Caregivers' level of depressive symptoms was twice as high as that of non-caregivers, the researchers found. They also had lower proliferation of immune system cells known as T cells, but higher production of proteins that promote inflammation.
And their telomeres were significantly shorter than those of the control individuals, the team reports in The Journal of Immunology.
The caregivers also had greater activation of telomerase, the enzyme responsible for repairing telomeres. "The increased basal telomerase activity in PBMC and T cells may reflect the attempt of immune cells to compensate for the excessive loss of telomeres of caregivers," the researchers surmise.
"We now have a mechanistic progression that shows why, in fact, stress is bad for you," said Kiecolt-Glaser, "how it gets into the body and how it gets translated into a bad biological outcome."
SOURCE: The Journal of Immunology, September 15, 2007.