Turn back the clock by reducing stress
Chronic stress takes a toll on the body, triggering premature aging
of immune system cells, new research suggests.
"People who are stressed over long periods tend to look haggard,
and it is commonly thought that psychological stress leads to premature
aging and other ... diseases of aging," writes lead researcher
Elissa S. Epel, PhD, a professor of psychiatry at the University
of California at San Francisco.
But exactly how chronic stress "gets under the skin"
to do its damage has not been understood, Epel writes. Chronic stress,
the focus of numerous studies, has been linked with poor health,
heart disease, and lower immunity.
In it, Epel and her colleagues examine one sign of biological aging
-- tiny segments of DNA and protein, called telomeres, that cap
the ends of chromosomes. Each time a cell divides, a portion of
this DNA erodes. After many cell divisions, so much DNA is missing
- and the telomeres are so short -- that the aged cell stops dividing,
she explains.
As cells age, they produce less and less telomerase, an enzyme
that adds DNA onto the telomeres. Both telomere length and telomerase
levels can therefore indicate a cell's "age," she writes.
That's when risk of disease increases.
"The results were striking," says co-author Elizabeth
Blackburn, PhD, professor of biology and physiology. "This
is the first evidence that chronic stress - and how a person perceives
stress - may damp down telomerase and have a significant impact
on the length of telomeres ... [causing] cellular aging."
To look more closely at whether chronic stress leads to telomere
shortening, Epel and her colleagues focused on 58 healthy women,
all either mothers of a healthy child or "caregiving mothers"
of a chronically ill child.
The mothers completed a brief questionnaire about chronic stress
in their lives over the past month. Then a blood sample from each
was analyzed to determine telomere length and telomerase activity.
As expected, surveys showed that caregiving mothers had higher
stress levels than mothers of healthy children.
Total years spent tending a sick child made a big difference. More
caregiving years translated into shorter telomeres and lower telomerase
activity.
But there was another key finding in the study: A mother's telomere
length was related to her perceived stress level -- whether her
child was chronically ill or not.
In translating telomere length into years of aging, researchers
determined the cells from the highly stressed mothers had aged from
nine to 17 additional years compared with the cells from the low-stress
mothers.
"The exact mechanisms that connect the mind to the cell are
unknown," writes Epel. "While psychological stress seems
to cause telomere shortening and cell aging, it's possible that
some people are less vulnerable to [chronic] stress - and therefore
have longer telomeres."
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