Scientists have identified the first direct link between stress and aging, a finding that could explain why intense, long-term emotional strain can make people get sick and grow old before their time.
Chronic stress appears to hasten the shriveling of the tips of the bundles of genes inside cells, which shortens their life span and speeds the body's deterioration, according to a small, first-of-its-kind study involving mothers caring for chronically ill children.
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Graphic: Stress and Telomeres
If the findings are confirmed, they could provide the first explanation on a cellular level for the well-documented association between psychological stress and increased risk of physical disease, as well as the common perception that unrelenting emotional pressure accelerates the aging process.
"There is this deeply held belief that stress leads to premature aging. But there is no hard evidence for how this might happen," said Elissa Epel, a psychiatrist at the University of California at San Francisco (UCSF), who helped conduct the research. "This is the first time that psychological stress has been linked to a cellular indicator of aging in healthy people."
The findings could lead to new ways to detect the early physical effects of stress and monitor whether attempts to alleviate its effects are working, she said.
While cautioning that the findings need to be confirmed by additional research, other scientists said the results represent an unprecedented step in deciphering the intricacies of the mind-body connection.
"This is a real landmark observation," said Robert M. Sapolsky of Stanford University, who wrote a commentary accompanying the paper in today's issue of the Proceedings of the National Academy of Sciences. "This is a huge interdisciplinary leap . . . a great study."
Dennis H. Novack, who studies the link between emotions and health at Drexel University College of Medicine in Philadelphia, agreed.
"Everybody's trying to figure out what causes aging and premature aging. We all know that stress seems to age people -- just look at the aging of our presidents after four years," he said. The new study "demonstrated that there is no such thing as a separation of mind and body -- the very molecules in our bodies are responsive to our psychological environment."
Epel and her colleagues studied 39 women ages 20 to 50 who had been experiencing grinding stress for years because they were caring for a child suffering from a serious chronic illness, such as autism or cerebral palsy, and 19 other very similar women whose children were healthy.
The researchers examined structures inside cells called telomeres. Telomeres are the caps at the ends of chromosomes -- the molecules that carry genes. Every time a cell divides, telomeres get shorter. In the natural aging process, the telomeres eventually get so short that cells can no longer divide, and they then die.
As more and more cells reach the end of their telomeres and die, the inexorable process produces the effects of aging -- muscles weaken, skin wrinkles, eyesight and hearing fade, organs fail, and thinking abilities diminish.
The researchers also measured levels of an enzyme called telomerase, which helps rebuild telomeres to stave off this process. Telomerase levels naturally decline with age.
"As the telomeres shorten, telomerase is trying to keep up," said Elizabeth Blackburn, a professor of biology and physiology at UCSF who helped conduct the study. "Over the long term, we lose the race and our telomeres do get shorter."