Narrator: This is Science Today. A recent University of California, San Francisco study found that chronic stress affects molecules that play a key role in cellular aging and possibly, the development of disease. Psychologist Elissa Epel, who led the study, measured a type of DNA that caps the ends of chromosomes, called telomere length, as a predictor of a cell's age, and also measured telomerase activity.

Epel: Telomerase is an enzyme that buffers the telomere, protects it and promotes it's lengthening. So we examined telomerase as an early precursor, an indicator of what might happen to the telomere.

Narrator: In a sample group of mothers caring for disabled children, Epel found that moms with the highest perceptions of stress had lost an amount of DNA in their telomeres that one would expect during the normal aging process of 13 years. This data is leading the researchers to now study heart disease.

Epel: That's because number one, there are lots of links in the literature showing that people with heart disease have much shorter telomeres in their white blood cells.

Narrator: For Science Today, I'm Larissa Branin.