Coming of age

Using a walker for balance, the state’s oldest resident makes her way slowly down the long driveway at her niece’s Berkshires farm to the road’s edge, then back again, every day. She just finished “1776’’ by David McCullough. Today, she turns 110, a milestone that ranks her among the world’s oldest people, but takes no medicine, not even a daily vitamin.

While Madigan’s physical health and mental acuity make her a medical marvel, her longevity reflects a sharp rise in the ranks of centenarians and hints at more dramatic demographic shifts to come. With striking medical advances and steady improvements in nutrition and lifestyle, average life spans are increasing at an unprecedented rate, swelling the over-100 population from a few thousand in 1950 to more than 300,000 worldwide today.

Over the next three decades, the number of centenarians is projected to grow to 2.3 million, according to a US Census Bureau report released this week. In the United States, the number of centenarians is expected to surge from an estimated 74,000 today to 600,000 by midcentury, a rise that specialists say will profoundly affect nearly all aspects of life.

But while far more people are living to 100 and beyond, 110 remains a rarefied threshold, researchers said. In in dustrialized countries, just 1 in 7 million people live that long.

“We know that the number of centenarians are increasing exponentially, and you would think that would lead to more people living to 110,’’ said L. Stephen Coles, director of the Gerontology Research Group in Los Angeles. “But it’s not true. It appears to be a kind of magic club.’’

Madigan’s life touches three centuries and spans a dizzying array of changes. Born when cars barely existed, she came of age at the close of World War I. She attended Warren G. Harding’s inauguration and recalls, with remarkable clarity, the advent of radio and television, Pearl Harbor and President Kennedy’s assassination.

With a clear voice and wistful look, she recounts moments like getting in trouble as a teenager for playing a swing song on the church piano and the day she met her husband in the early 1920s. Gazing at a black-and-white portrait of herself from that time, she touched with a furrowed finger the image of her long-past youth.

Yet, Madigan lives decidedly in the here and now, and believes that is why she is still here. Looking forward to each new day, she is sure, makes it more likely that another will come.

“I try to take each day as it comes, and cherish it,’’ she said. “I love my life, and have a lot to live for.’’

Some 200 people, many from the Washington, D.C., area where she spent most of her life, are expected to attend a birthday celebration tomorrow for Madigan, a winsome spirit with a winking wit who is affectionately known as “Aunt Bennie.’’

Coles, who recently interviewed a 111-year-old woman from Los Angeles who still smoked, said genes, not behavior, are the key to long life. Yet DNA alone does not determine destiny, specialists said. People who live to such advanced age do so, in part, from sheer will.

“These people are universal in their desire to live,’’ Coles said.

Madigan believes she is living proof. She doesn’t doubt the genetic component, but notes that her parents didn’t live particularly long lives, and neither did her two siblings, who died of cancer. She never exercised much and was known to have a scotch or two, though she gave it up in recent years.

She expresses deep affection for friends, family, and simple, everyday things she said make life worth living. She bakes fudge, slurps Jell-O, nibbles at chocolate. She solves jigsaw and word-search puzzles. She dotes on her great-great-nieces and nephews. She spends hours on the back porch, watching the clouds and the breeze in the trees.

Last fall, she came down with pneumonia, and doctors said there wasn’t anything they could do. She went into hospice care, and relatives assumed the end was near. Madigan thought otherwise.

“I made up my mind it wasn’t,’’ she said. “And here I be.’’

Born in West Springfield, Madigan moved to Cheshire when she was 6, and after graduating from Adams High School in 1918, she moved to Washington, where she worked as a secretary for the Veterans Administration, then the Treasury Department. She and her husband met a few years later, and while they never had children, enjoyed a rich life with friends.

After retiring in 1942, she volunteered with the church and at nursing homes, where she played the piano for residents. After her husband died in 1976, she stayed active with a group of friends near her home in Silver Spring, Md. But as the years passed, so did many of those dearest to her.

By nearly any measure, Madigan represents the best-case scenario for such advanced age. She lived independently until a few years ago, when decreased mobility persuaded her to move to her niece’s farm.

Thomas Perls, a Boston Medical Center geriatrician who directs the New England Centenarian Study, said Madigan’s good health is typical of those who reach such advanced age. They have to stay relatively healthy, he said, to survive so long.

“That’s the wonderful news of living to 100, it really is worth it,’’ he said.

This week, Kathy West, a family friend, visited Madigan to give her two birthday presents - a hand-knit quilt for party guests to sign and a photo album she fashioned from a skirt Madigan once wore.

“That is beautiful, Kathy,’’ she said. “That belongs in the parlor. You’re real sweet to me.’’

“These are the kind of people,’’ she added softly, “who keep you going.’’