Some shortcuts to long life

Last week, I turned 60 – a milestone in anyone’s life. After all, according to our laws, I am now a senior citizen! Imagine, I can now buy medications at 20 percent discount! But really, I thank God that I am in relatively good health and I hope that I will be able to practice healthy aging as I get older.

Indeed, the swelling of the population of older people including those 100 and over, all over the world, has given researchers an opportunity to answer some of the most fundamental questions about human health and longevity: What does it take to live a long life? How much do diet, exercise, and other lifestyle factors matter compared with "good" genes?

And perhaps most importantly, what is the quality of life among the elderly?

Does getting older inevitably mean getting sicker, or can people remain productive, social, and independent when they get old?

Centenarian Studies

To answer these questions, there are a dozen or so centenarian studies to learn from. The New England Centenarian Study started with 46 people, aged 100 and over, in the Boston area but is now recruiting people from throughout the United States. A health advice book has been recently published on findings from the centenarian study in Okinawa, where the average life expectancy of 81.2 years, is the highest in the world. I wrote about this in my column on Feb. 26, 2002. There are ongoing centenarian studies in Italy, Sweden, and Denmark. For the most part, results from these studies belie the myth that the oldest are doddering and dependent. Some harsh demographic selection may come into play. Frail individuals die sooner, leaving only a relatively robust group still alive. In fact, one of the rewards of living a long life is that, for the most part, the "extra" years are healthy years.

Physical activity is a recurring theme: The people in these studies are walkers, bikers, and golfers. In Okinawa, centenarians do tai chi and karate. People who live to 100 and beyond exercise their brains, too, by reading, painting, and playing musical instruments. Some continue to work, an indication that our love affair with retirement may be a mixed blessing.

Good Genes

Traits that run in families are not necessarily genetic. After all, families often share the same eating habits, activity levels, and other so-called environmental factors that influence health. Still, similarities within families are often a good clue of strong genetic influence, and longevity does seem to run in families. The New England Centenarian Study, for example, has found that its subjects were four times more likely to have a sibling who lived past 90 than people with an average life span.

Now, the search is on for genetic attributes. Researchers have previously identified some forms of a gene called apolipoprotein E that increases the risk for cardiovascular disease and Alzheimer’s disease. Studies have shown that those dangerous variants are rare among centenarians. And scientists have had success building long life into some animals. They’ve genetically engineered a strain of fruit fly to live 35 percent longer than normal strains. Certain mice genes have been mutated so the animals live 30 percent longer than normal.

No one has found such mutation in people. But last year, Thomas Perls, director of the New England Study, and Louis Kunkel, a molecular geneticist at Children’s Hospital in Boston, believe they got closer by identifying a section of chromosome 4 that may predispose people to long life. They made their discovery by scanning the genes of 137 sets of very old siblings – one person aged 98 or older with a brother who was at least 91 or a sister who was at least 95. The siblings shared this distinctive section of chromosome 4.

Advances In Health Care

But genes aren’t the whole story. Public health advances like sanitation and routine vaccination have greatly improved the odds for long life. Indeed, it may be the intersection of genes with ever-changing health conditions that really determines how long we live. Today’s centenarians may have survived so long partly because they had genes that protected them against infectious diseases prevalent in the early 20th century. Tomorrow’s centenarians may need to have a different kind of genetic advantage attuned to 21st century circumstances.

Medical interventions are starting to make a demographic difference, particularly with respect to mortality from cardiovascular disease. Most centenarians still die of heart disease, but they might have died much sooner without the medicines we now have to control cholesterol levels and hypertension.

Nutrition

Diet and other health habits play a role, too. Okinawans lose their actuarial edge when they move to Western countries and, presumably, adopt a more Western lifestyle. Italian researchers reported last year that healthy centenarians had exceptionally high blood levels of vitamins A and E compared with healthy young adults. The study didn’t address, however, what causes high levels. Still, the authors theorized that vitamin-rich blood may both strengthen the immune system of the centenarians and defend them against damage done by oxygen free radicals, the reactive molecules that some researchers believe are the principal cause of aging.

It’s not a centenarian study, but a large, long-term study of Seventh-Day Adventists in California has produced some valuable information about longevity because the Adventists, on average, live several years longer than their fellow Californians. By some reckonings, they even outlive the Okinawans. There is no reason to believe the Adventists have any special genes, so other factors explain their longevity. Researchers broke down their health habits in a statistical analysis published in the July 9, 2001 issue of the Archives of Internal Medicine. A great deal of physical activity, frequent consumption of nuts, not eating meat, and medium body weight each was found to add about 1.5 - 2.5 years of life.

Here are some lessons to be learned from the do’s and don’ts of centenarians:

• They don’t smoke or drink heavily.

• Those who had smoked didn’t do so for long.

• They gained little or no weight during adulthood. Being overweight makes people more vulnerable to many life-threatening illnesses, including heart disease, diabetes, cancer, and stroke.

• They don’t overeat. Okinawan centenarians consume 10 to 20 percent fewer calories per day than the typical Western diet. And in animal studies, calorie-restricted diets have consistently increased the life span. The old Okinawans consume less fat, too. About 26 percent of their energy intake comes from fat, compared with 30 percent or more for Americans. And more of that fat is beneficial –omega-3 fatty acids and unsaturated fats found in vegetable oils.

• They eat many fruits and vegetables. The Okinawans have an average of seven servings a day.

• They get regular physical activity for as long as they are able. Strength-building activities such as climbing stairs or lifting small weights are especially beneficial because they help slow the age-related loss of muscle mass.

• They challenge their minds. Stimulating mental activity may help prevent age-related thinking and memory problems by stimulating communication between brain cells. Particularly among elderly men, decreased cognitive performance is strongly associated with mortality.

• They have a positive outlook. Perls says centenarians seem to have personalities that shed stress easily. An inability to control emotional stress has been linked to memory loss and heart disease.

• They are friendly and maintain close ties with family and friends. Not surprisingly, positive relationships are associated with lower rates of depression. And lower rates of depression may result in lower rates of heart disease.

Many researchers think that people could add up to a decade to their lives if they emulate the centenarians. And, from what we know so far, they aren’t doing anything mysterious. They’re simply following the standard health commandments: Don’t smoke, keep trim, get exercise, manage stress, and avoid social isolation!