Stress has long been known to impact health. During emotionally tough times, our faces grow haggard and new wrinkles appear. We may even develop an illness.
Yet "the exact mechanisms of how stress gets 'under the skin' remain elusive," Elizabeth Blackburn and her colleagues wrote in a ground-breaking 2004 study examining aging.
The paper showed women under chronic stress — all responsible for caring for a chronically ill child — had DNA on average a decade older than a control group of women caring for a healthy child. With their work, Blackburn and her colleagues may have discovered how stress ages us at the cellular level.
To understand how it works, consider an ordinary strand of DNA. As the cells in your body divide throughout life, each division produces two nearly exact copies of the original cell — except for one thing. Each time a cell divides, it loses a tiny bit of the "cap," called a telomere, at the end of the DNA in each cell.
As a result, over the human lifespan, those telomeres become shorter and shorter: an infant has about 8,000 of the base pairs that make up DNA in each telomere. An adult will have around 3,000 base pairs, while someone over 65 will have just 1,500.
In an added "wrinkle," the enzyme teleromase (discovered by Blackburn and her student Carol Greider in 1985) acts as a last-minute savior for those ever-shortening strands of DNA, staving off further shortening — and thus cell death — by adding base pairs. Yet after about 50 to 70 cell divisions, human cells have so little DNA left, they're no longer able to replicate and die off.
Blackburn's 2004 study found that the longer a woman had been caring for a chronically ill child, the shorter her telomere length and lower her teleromase activity. In fact, telomere length was connected to stress in both groups of mothers, even among those with healthy children: the higher a woman's perceived stress, no matter the health of her child, the shorter her telomeres.
It may be one of the more startling — and far-reaching — medical discoveries of our era. In recognition of her achievement, Blackburn won the Nobel Prize in physiology or medicine in 2009 (shared with Greider and another colleague, Jack Szostak) for the discovery of how telomeres and teleromase protect DNA.
It's recent science, and the story continues to unfold. In 2013, Dean Ornish, MD, a well-known alternative medicine researcher, took things a step further. In a small pilot study co-authored with Blackburn, among others, Ornish was able to show that telomere length and teleromase activity are not set in stone, but variable — and can increase with lifestyle changes.
Ornish put 10 men with low-risk prostate cancer on a fairly rigorous program that included mindfulness meditation along with other lifestyle changes (a healthy, plant-based diet, daily exercise, and social support in the form of a weekly support group). Another 25 men with low-risk prostate cancer, acting as controls, followed a "watchful waiting" protocol, the standard care, but made no other changes to their habits. At the end of five years, the 10 men in the intervention group had increased their telomere length by 10 percent — and the more they adhered to the recommended lifestyle changes, the longer their telomeres. Meanwhile, telomeres among men in the control group shrunk by 3 percent, a rate that is about average as we age.
It may be that medical science is narrowing in on the age-old adage that stress will age you — and finding out exactly how it happens. Another study published this year found rates of aging diverge sharply, even among relatively young people. The authors measured physiological characteristics in nearly 1,000 people. Based on standard health measures such as cholesterol and blood pressure, as well as telomere length, they found "biological ages" of as young as 30 to as old as 60 in that group — all aged 38. What's more, students assigned to guess participants' ages from photos found those with "older" biological characteristics actually looked older, too.
Scientists aren't yet sure whether telomere shortening is a cause or merely a symptom of aging, like gray hair. The topic is hotly debated. Yet there are hints it may be directly causal, some say: telomere length may be a better predictor of risk of aging-related conditions such as heart disease, diabetes, and cancer. Other conditions (such as dyskeratosis congenita and aplastic anemia) are characterized by shortened telomere length and lead to early death.
Is there a test to find out your own telomere length? One company, SpectraCell, claims to offer the first commercially available such test in the United States. Blackburn is also part of a company, Telome Health, that also says it's working on a test for consumers, though plans to develop it appear to have stalled. If you're interested in finding out more, ask your doctor for help.
The good news: even something as simple as mindfulness meditation can slow telomere shortening. While we may not always be able to avoid stress, reframing it as a challenge can also help, Blackburn's research has found. Exercise, a healthy diet, and not smoking will also keep telomeres longer — and, emerging science suggests, you younger.
November 16, 2015
Christopher Nystuen, MD, MBA