Hitting the genetic jackpot

Exceptional aging a rarity

Your environment — including food choices, exercise habits and sun exposure — contributes the most when it comes to living to an average age. But it is your genes that determine how likely you are to live to an exceptional age.

“We define exceptional age as the top 1 percent survival rate in a particular birth year cohort,” says Assistant Professor Harold Bae, who investigated the role of genes on longevity in a recent study published in the Journals of Gerontology: Biological Sciences.

“For example, in the New England Centenarian Study, the birth year cohort is 1900. That means that males age 96 and older and females age 100 and older have reached exceptional age.”

Harold Bae

CPHHS Assistant Professor Harold Bae

One example of our genes’ influence on exceptional aging is on siblings. Male siblings of centenarians are 17 times more likely than other men born around the same time to reach 100, and female siblings are 8.5 times more likely to reach 100.

A gene debunked

Harold and his team looked closely at genetic data in the blood samples of 2,072 subjects from four centenarian studies. One of the most interesting findings was that a gene called FOX03, which the scientific community has been widely studying for a decade, has less of an impact on exceptional aging than previously thought.

“The definition of longevity wasn’t consistent in prior studies,” Harold says. “The data shows that as subjects got older, the effect of FOX03 went down and there was no survival benefit over the age of 95.”

“We don’t think that it’s a single gene,” he adds. “It looks like it’s a combination of genes, and that when they work together they’re able to push your health span closer to life span, which is related to a hypothesis introduced over 35 years ago called compression of morbidity.”

Compression of morbidity was coined by James Fries of Stanford University in 1980. He theorized that most illness is chronic and occurs later in life — and that the lifetime burden of illness could be reduced if the onset of chronic illness could be postponed.

People living to exceptional age typically have an elongated health span close to life span, meaning they live in a healthful state until just a few years before they die. Those who live an average lifespan typically have a shorter health span and suffer longer in their later years.

Control the average

The average lifespan for Americans is currently 78.8. The good news for the majority of the population who won’t reach exceptional longevity is that 70 percent to 80 percent of normal aging is within our control in the choices we make daily for our health and well-being.

Harold cites the Seventh Day Adventists as an example. “This is a population that doesn’t engage in a lot of risky behaviors,” he says. “They don’t smoke or drink and they eat well, and their lifespan is eight to 10 years longer than average.”

Because the healthy aging and longevity gene combination remains unknown, Harold and his team are focusing their efforts on using more advanced statistical techniques to combat small sample size. The more he can study these prodigious individuals, the more we can learn about living the longest — and healthiest — life possible.

Calling all supercentenarians 

Living to 100 has its benefits, such as a longer health span and special words to designate the milestone.

  • A centenarian is someone who has reached 100 years of age. Occurs at a rate of about 1 in 5,000.
  • A semi-supercentenarian is someone between the ages of 105–109. Occurs at a rate of about 1 in 250,000.
  • A supercentenarian is someone who is 110 years of age or older. Occurs at a rate of about 1 in 5 million.

According to a 2010 report published by the United States Census Bureau, the number of centenarians nationally is on the rise.

In 1980, there were 32,194 or 1.42 in every 100,000 people that were centenarians. In 2010, the number grew to 53,364 or 1.73 in every 100,000.

In 2010, centenarians were overwhelmingly female – 82.8 percent female versus 17.2 percent male.