The golden age of aging
To me, old age is al-ways 15 years older than I am.”
This quip about old age existing perpetually in the distant future came back to my mind a few days ago as I was planning to celebrate my 69th birthday tomorrow. It comes from Bernard Baruch, the American financier who, incidentally, was a great supporter of my medical specialty Physical Medicine and Rehabilitation. I found it in Barlett’s familiar quotations actually a pretty good source for historical attitudes towards growing old. Baruch (who lived to 94) had something positive to say, but Shakespeare was not so reassuring. The “seventh age of man” was nothing to look forward to. In Shakespeare’s time, 50 was a ripe old age.
Researchers, inspired by the latest science on aging, are calling into question the many expected negative aspects of growing old. They say there’s reason to look forward to a golden age of aging. Seniors today are living more independently; there’s less of them dying of lengthy and debilitating illnesses due to improved screening and better treatments; and they’re happier than they were in the past, according to a 2008 University of Chicago study. There is a need to rethink our ideas about old age, this school of thought says, and realize that it can be a positive and productive stage in one’s life.
Adding years to life
Researchers are finding out that the aging process is remarkably elastic and that it can be manipulated. The lives of laboratory animals, for example, have been dramatically stretched by tweaking their genes, changing their diets, and giving them drugs. The question is whether these techniques would also work safely in human beings.
Cynthia Kenyon, a geneticist at the University of California San Francisco, found in the 1990s that by tampering with a single gene associated with aging in nematodes, a roundworm no bigger than a comma in this sentence, she could double their normal three-week life span. When this gene was deactivated, she found it kicked in a “fountain of youth” gene that improved the worm’s defenses against diseases. The nematodes lived longer and stayed younger. Now, Kenyon is hunting for drugs that could turn on the fountain of youth gene in human cells.
If the secret of slowing down human aging could be understood, it would certainly be one of the greatest advances in medical history. While aging itself is not a disease, postponing it would simultaneously also postpone our most dreaded diseases like cancer, heart disease, stroke, and Alzheimer’s.
Let us consider three hot topics currently under investigation in the field of longevity research: cutting calories, exercise, and deciphering the genetics of the oldest of the old.
Lower-than-normal-calorie diet
Hundreds of studies since the 1930s have shown that below-normal intake of calories slows aging and greatly extends healthy life spans in organisms as simple as yeasts and as complex as rats. The journal Science has reported that rhesus monkeys whose daily calories were reduced by 30 percent for 20 years had only one-third the usual risks, as compared to normally fed monkeys, of developing age-related illnesses such as diabetes, heart disease, cancer, and brain deterioration. That suggests “quite convincingly” that their aging is being slowed, says Richard Weindruch, a professor of medicine at the University of Wisconsin whose group is leading the ongoing study. He’ll have to wait a good while though to see if these rhesus monkeys will live longer, as they have been known to live for 40 years.
What scientists hope is to understand how restricting calories prolongs life. Once the mechanics is understood, then maybe, they can produce the same effects using other methods. Maybe, in the future, you can just pop a pill to delay aging!
Exercise and longevity
Exercise can’t stop the years from ticking by, but it certainly appears to protect against some of the diseases of aging. The latest evidence: a study showing that the white blood cells of endurance athletes had longer telomeres the tiny, protective units of DNA that cap the end of chromosomes like plastic shoestring tips and grow shorter as cells age.
The results may explain how exercise can protect against two big killers: heart disease and cancer. “Younger” white blood cells may be able to clear out more efficiently both abnormal cells before they progress to cancer or to plaques that block the coronary arteries.
Some scientists believe that exercise may inhibit various hormones in the body that stimulate the growth of cancer cells. Inflammation and immunity also are thought to play a role in cancer, and exercise seems to clamp down on inflammation and boost immunity.
Moreover, specific cancers are uniquely affected by exercise. The reason that colon cancer is believed to be reduced by exercise is that it decreases the time food (and any carcinogen) spends in the digestive system. It is also thought that breast cancer may be caused by both inflammation and estrogen exposure; exercise cuts the amount of circulating estrogen and may cause changes in the menstrual cycle that reduce the exposure over many months or years.
Somehow, exercise seems to preserve brain function as well. There’s evidence from animal studies that regular physical activity may help generate new neurons; it may also help create new blood vessels that forge connections between neurons. And it might be that even if the plaques implicated in Alzheimer’s disease appear, they would have a lesser impact as they would on someone who is a couch potato!
The secret of the oldest old
In 1999, Thomas Perls published a book, Living to 100, which described the findings of the New England Centenarian Study. It was found that the vast majority of the centenarians in the study sample were doing surprisingly well. Most were free from disabilities until the end of their lives even those contending with significant age-related ailments, like heart disease. And the one out of seven million people who reaches the “supercentenarian” age of 110 and beyond (there were 85 in the study) seems to avoid not only the effects of age-related conditions but also the illnesses themselves. Or if these rare individuals do become ill at the end of their lengthy lives, they quickly die rather than languish in declining health.
What is the secret of the oldest old? “Our hypothesis is that centenarians get to be 100 because they have protection against age-related diseases and maybe against aging itself,” says Nir Barzilai, director of the Institute for Aging Research at the Albert Einstein College of Medicine in New York, who has studied Ashkenazi Jewish centenarians and their children for a decade. “When you ask them why they live so old, you get this fascinating story . . . They’ve done nothing right. Some have been smoking for 95 years. And there’s no one who exercised regularly!”
Both Barzilai and Perls are hunting for hints to healthy longevity in those who hit 100 to learn what it is about their genetic makeup that seems to help them along and whether that could help those of us with fewer genetic gifts. Nearly a quarter of Barzilai’s several hundred centenarians, for example, have a genetic mutation that bestows on them levels of “good cholesterol” as high as triple the normal concentration, he says. He has found that those with this genetic mutation are also largely immune to Alzheimer’s disease and apparently, have lower risk of heart disease, high blood pressure, and diabetes.
What about the majority of us who didn’t “win the genetic lottery at birth”? Well, the truth is, we could add many years to our lives even now. “We are living about 10 years less than our potential . . . mostly due to our bad health behaviors,” says Perls. Evidence comes from groups of similar individuals who do the right thing. Seventh-Day Adventists, for example, have an average life expectancy of about 88 years, the highest in the US. (The US average is 78.) Adventists avoid red meat (many are vegetarians), exercise regularly, and don’t drink alcohol or smoke. Their focus on religion and family may ease stress, itself a risk factor. “That’s kind of the recipe,” says Perls. And it’s one that doesn’t rely on research breakthroughs either!
What’s the moral of the story? That right now, we have already the means even without further research not only to add years to life but also to add life to those years. And here’s another quote from Barlett’s by the California poet Robinson Jeffers: “The heads of strong old age are beautiful/Beyond all grace of youth.”
Here’s to healthy aging!
