The link between chronic stress and a marker of old age is being disentangled
TELOMERES are to chromosomes what plastic caps are to shoelaces—they stop them fraying at the ends. Unlike shoelaces, though, chromosomes replicate themselves from time to time as the cells they are in divide. This shortens the telomere and, after 50-70 such divisions (a number known as the Hayflick limit, after its discoverer), a chromosome can grow no shorter and the cell it is in can divide no more.
That provides a backstop against cancer. The rapidly dividing cells in a tumour soon hit the Hayflick limit and the process is brought to a screeching halt. Which is a good thing. The bad thing is that reaching the limit is one of the markers of old age. You do not want it to happen too quickly, particularly in tissues that have to do a lot of dividing in order to work properly, such as those in the immune system.
It has been known for some time that chronic stress (caring for a child with a protracted illness, for example) causes premature shortening of the telomeres. What has not been clear is whether this is a one-way trip, with each stressful period turning the telomeric ratchet irreversibly. This week, though, at a meeting of the American Association for Cancer Research in Orlando, Florida, a group of researchers led by Edward Nelson of the University of California, Irvine, showed that it isn’t. Their research suggests that stress management not only stops telomeres from shortening, it actually promotes their repair.
Dr Nelson drew this welcome conclusion from a previous study that measured the impact of telephone counselling on women who had been treated for cervical cancer. The study found that such counselling worked, both mentally and physically. Women who had been counselled reported that the quality of their lives had improved, compared with those of a control group who had not been counselled. They also showed improvements in the strength of their immune systems.
Given those benefits, Dr Nelson wondered if he could find others, and he re-examined the participants’ samples to look at the lengths of the telomeres in their white blood cells (red cells have no nuclei, and therefore no chromosomes). What he found surprised him. Not only did counselling stop telomere shrinkage, it actually promoted telomere growth. Those women for whom counselling had worked (ie, those who reported a decrease in emotional stress) had longer telomeres at the end than they did at the beginning. Their Hayflick countdowns were being reset.
A single such result must, of course, be treated with caution. But another study reported at the meeting, by Elizabeth Blackburn of the University of California, San Francisco (who shared the Nobel prize for the discovery of the enzyme that repairs telomeres), gave some support. This showed that exercise has a similar effect to counselling on the telomeres of the stressed.
If Dr Nelson’s work is successfully replicated, it will shine more light on the ill-understood relationship between the health of the mind and the health of the body. For, as he points out, nothing actually changed in the lives of the women in question. They still had cancer, albeit under treatment, and they were still under stress. Nothing, that is, except their attitude.