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Stop stressing!
01/12/2004 09:56 - (SA)
Los Angeles - Chronic stress appears to shorten the life of the body's immune cells and may compromise the body's ability to fight off disease, US researchers said on Tuesday.
In a small study looking at the effect of long-term psychological stress on the body, US researchers found that the immune cells of mothers of chronically-ill children aged at a much faster pace than those of women with healthy offspring.
In fact, one of the molecules that is believed to play a key role in cellular ageing had aged the equivalent of 10 years more in the women reporting the most stress than in the women in the lowest-stress group.
Previous studies, and anecdotal evidence, have shown that chronic stress can take years off a person's life, but the mechanism underlying the mind-body link has eluded scientists until now.
The authors of this study said while they could not definitively identify the mechanisms at work, the evidence suggested that mental anxiety, probably mediated through stress hormones, was inhibiting a molecule crucial for the reproductive life of the cell.
Shown to damage DNA
The molecules - DNA-protein complexes called telomeres - influence the number of times a cell divides, its health, and its life span, factors which in turn affect the health of the tissues that cells form.
In the group of women reporting the most stress, the length of the telomeres was shorter than in the women with the least stress, the authors noted.
The enzyme telomerase which protects the telomeres was also less active in the stressed-out group, and they had higher levels of oxidative stress than their more mentally healthy peers, the study said.
Oxidative stress has been shown to damage DNA.
"The results were striking," said Elizabeth Blackburn, a co-author of the study, and professor of biology at the University of California at San Francisco.
"This is the first evidence that chronic psychological stress ... may modulate the rate of cellular ageing."
The researchers, who reported their findings in the Proceedings of the National Academy of Sciences, cautioned that their findings are preliminary, and were based on a study involving just 58 women between the ages of 20 and 50.
They said they aim to investigate whether chronic psychological stress has an impact on telomeres in other types of cells, such as cells of the lining of the cardiovascular system.
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