[By Jenyne Simmons]
There’s no denying the inevitable ticking of our ageing clock with each passing day, but what are the factors that will decide if you will be a centenarian?
Scientists have been interested in the study of longevity for many years. What makes a person live past a hundred while another to succumb to a heart attack at 50? A boom in centenarians is just around the demographic bend; the National Institute on Aging predicts that their number will grow from the 37,000 counted in 1990 to as many as 4.2 million by 2050. Pharmaceutical companies and the National Institutes of Health are throwing money into longevity research. Major medical centers have built programs to satisfy the demand for data and, eventually, drugs.
What have the researchers learned? Studying a group of “SuperAgers”, scientists theorized that they must have something that protects them from all major health issues throughout their lives— heart problems, stroke, cholesterol etc. Otherwise, when they didn’t have a heart attack, say, at 78, they’d have succumbed quickly to the next thing on their body’s inscrutable list. So instead of looking, as most genetic studies do, for pieces of DNA that correlate with the likelihood of getting diseases, researchers looked for the opposite: genes that correlate with the likelihood of not getting them—and thus with longevity.
#1 Family History
The top correlate for longevity is one that requires no blood test to discover: having a SuperAger in your family already. Study has so far identified, or corroborated, at least seven associative markers. The most significant is the Cholesterol Ester Transfer Protein gene, or CETP, which in one unusual form correlates with slower memory decline, lower risk for dementia, and strongly increased protection against heart disease. (Among other things, it increases the amount and size of “good” cholesterol.) Only about 9 percent of control subjects have two copies (one from each parent) of the protective form of CETP, while 24 percent of the centenarians do.
Other markers found more frequently among the SuperAgers include a variant of the APOE gene that protects against atherosclerosis and Alzheimer’s, a variant of the FOXO3A gene that protects against tumor formation and leukemia, and a variant of the APOC3 gene that protects against cardiovascular disease and diabetes. (This variant alone has been associated with an average life extension of four years.) Having long telomeres—regions at the ends of chromosomes that shorten as you age—is another kind of marker, acting as an instant-read longevity thermometer. There’s evidence, as well, that small stature among the SuperAgers may reflect the influence of a protective factor seen throughout nature; ponies live longer than horses.
An Einstein study published in August asked whether the SuperAgers, over the course of their lives, had better health habits than the general population. The answer was no; their habits were, if anything, worse. They smoked as much or more than others and were no better about diet or exercise. Exercise was sporadic and mild. Something else is at play. When asked what they themselves thought it might be, the participants offered such explanations as genes, luck, and family history. And even “God”.
In conclusion, SuperAgers do not age differently from other people, just later. Much later. Many do eventually get hit by one of the big four, or by other catastrophic problems, but 30 years after the rest of the population. The average age at which American women have a first stroke is 72; some SuperAgers get theirs past the age of 100.
Already, thanks to stents and pacemakers and bypass surgery, some people who, a generation ago, might have been dead at 75 are muddling through their eighties, albeit half-broken and medicated to the gills. Jeanne Calment—the longest-lived human who could prove it with a birth certificate—died in 1997 at the age of 122.
In any case, researchers are plotting alternate routes. Currently under way at Merck are Phase III trials of a drug that mimics the action of the CETP variant that has shown to correlate with cardiovascular and cognitive health in the SuperAgers. The results are expected in 2013.
Eventually, drug companies will cash in on the silver dollar and develop all such markers into longevity drugs and to “achieve a greater health span within our potential maximal life span.” However worthy that sounds, it’s unclear to me whether the baby-boomers who may be the first beneficiaries of such death-delaying drugs are hardy enough to endure the extra decades of non-lethal afflictions they will face instead. Still, the temptation of longevity cannot be denied, and this will be one area where interest and research will shine their spotlight in the years to come.