The Effect of Psychological Stress on Telomeres

In the film The Holiday, Cameron Diaz exclaims “Severe stress…causes the DNA in our cells to shrink until they can no longer replicate.” Did Hollywood get the science right? Do people who are stressed have shorter telomeres? To answer that question, Nobel laureate Elizabeth Blackburn and colleagues measured the lengths of telomeres in mothers of chronically ill children. What could be more stressful than having a sick child? The longer a woman had spent being the primary caretaker of her ill child, the shorter her telomeres. The extra telomere shortening in the most stressed mothers was equivalent to that caused by a full decade of aging. The same was found in caregivers of Alzheimer’s patients, raising the possibility that telomeres could be used as a “psychobiomarker,” an objective measure of life stress and adversity.

But some studies found opposing results: decreased telomerase activity among dementia caregivers vs. increased telomerase activity among a different set of dementia caregivers. Telomerase is the enzyme your body uses to repair and lengthen shortened telomeres. The researchers tried to explain this unexpected finding by suggesting that the elevated telomerase activity was an attempt by cells to counter the stress, but they can’t have it both ways. In a petri dish, exposing cells to stress hormones decreases telomerase activity, but when a group of older women was exposed to psychological stress in a lab setting (a public speaking task) telomerase activity jumped up within an hour.

The most “out of this world” experiment involved identical twin astronauts, Scott and Mark Kelly. Both started out with similar average telomere lengths but after nearly a year in space being bombarded by cosmic rays, Scott’s telomeres surprisingly lengthened compared to Earthbound Mark, suggesting a compensation response, but then rapidly shortened upon landing, ending up worse in the end.

Even if telomeres were consistently associated with past stress, anxiety… adversity in life… or a history of child abuse, there isn’t much we can do about our past. If we manage our stress now, can we grow back our telomeres? Those who practice meditation tend to have longer telomeres than those who don’t, but when actually put to the test, although there appeared to be some early success with mindfulness meditation interventions, when all the randomized controlled trials are compiled together there does not appear to be a significant effect on telomere length. This could be a consequence of the extent of meditation practiced. The meditators in the cross-sectional analyses and other non-randomized studies that did show a significant telomere difference averaged more than 3,700 hours of meditation practice, compared to only 36 hours in the randomized studies done to date.