In brief: Stress takes the ed... Health Article

In brief

Stress may not turn hair white overnight, but a study published in late 2004 shows that when prolonged, it can accelerate the aging of body cells, with obvious implications for health and longevity.

The chromosomes in the nuclei of our cells are capped and stabilized by structures called telomeres. The telomeres are maintained by an enzyme called telomerase, which declines in activity with age. Every time a cell divides, its chromosomes shred a little at the ends and its chance of survival is lowered. People with shortened telomeres are more likely to die.

In the study, scientists examined the leukocytes (infection-fighting white blood cells) of 58 healthy young women, 19 with healthy children and 39 who were under long-term stress because they were caring for a chronically ill child. After controlling for age and height–weight ratio, the longer a woman had been caring for a sick child, the shorter her telomeres and the less active her telomerase.

Shorter telomeres and lower telomerase activity appeared generally in women who said they were under stress, whether they were caring for a sick child or not. Judging by telomere length rather than chronological age, women in the top 25% for self-described stress were a remarkable 10–17 years older than women in the bottom 25%.

Subjective stress is not necessarily a cause of shortened chromosomes. It could be the other way around: people with intact telomeres are better able to resist psychological stress. The objective stress on women with sick children is a different matter. A woman’s telomeres could not affect the length of time she has been caring for a child.

Stress, whether self-described or objective, was also correlated with the activity of oxygen free radicals, as revealed by tests of the women’s urine. These chemically hyperactive products of metabolism combine with almost any tissue they encounter, and oxidative damage reduces the activity of telomerase.

Everyone is familiar with the idea that stress can cause premature aging and disease. The relationship between chronic depression and heart disease is well known, and there is evidence that chronic stress weakens the immune response. This research suggests how the process might work at the level of individual cells. Heightened activity of glucocorticoids (stress hormones) and the sympathetic nervous system raises the rate of oxidative damage, which accelerates the aging of leukocytes by shortening their telomeres.

Future researchers may be interested in other kinds of cells and other kinds of stress (physical rather than emotional, for example), as well as individual genetic differences in the vulnerability of telomeres to stress.

Epel ES, et al. “Accelerated Telomere Shortening in Response to Life Stress,” Proceedings of the National Academy of Sciences (Dec. 7, 2004): Vol. 101, No. 49, pp. 17312–15.

Sapolsky SM. “Organismal Stress and Telomeric Aging: An Unexpected Connection,” Proceedings of the National Academy of Sciences (Dec. 14, 2004): Vol. 101, No. 50, pp. 17323–24.