When David Snowdon finishes a talk to an audience of older people, frequently the first question they ask is: “What can I do to improve my chances of aging successfully?” His response comes in a single word: “Walk!”

He also recommends much else, such as keeping your brain active, eating good food with other people, and developing your spiritual life.

Dr. Snowdon knows a lot about successful aging. An epidemiologist, he founded the “Nun Study,” a now celebrated research project centered on the School Sisters of Notre Dame. This Catholic community of nuns agreed to take part in 1986 and, by this time, hundreds of them have participated.

In the first few years, while Dr. Snowdon worked at the University of Minnesota, the research was directed toward the connection between education and health in later life. When in 1990 he moved to the medical center at the University of Kentucky, Snowdon’s focus shifted to Alzheimer’s disease. Since that time, his work and that of his associates have become famous among researchers in the field of aging and have also received considerable media attention.

Snowdon rightly considers himself lucky to have found a congregation of religious sisters willing to cooperate with him. They are a researcher’s dream because they share so many life features in common. All unmarried, they live the same style of life and, moreover, their community has kept careful records of each of their members going back to the time they first joined.

It also has helped that David Snowdon was acquainted with nuns from childhood on and had some as teachers in elementary school. He has brought to his research a deep respect for the sisters, with many of whom he has developed close friendships.

At first he felt nervous about proposing to the nuns that they participate in his research. But the way was eased when one of the leaders of the community told him how to deal with the older sisters: “We treat them with the care and respect they deserve. We will expect nothing less from you.” And, to judge from “Aging With Grace,” the book Snowdon authored last year, he has followed through.

The researcher felt even more nervous when he made another, more threatening request of the sisters. He asked them to donate their brains to his study. To his relief, the sisters responded generously, with 678 agreeing to have their brains studied after their death. They based their decision on spiritual motives fundamental to their faith. One said: “It is the spirit that is important after death, not the brain.” And another added: “Resurrection does not depend on how our bodies are in the grave.”

The donors saw the decision as expressing the service of their neighbors to which their whole life had been dedicated. One leader explained this orientation: “As sisters, we made the hard choice not to have children. Through brain donation, we can help unravel the mysteries of Alzheimer’s disease and give the gift of life in a new way to future generations.”

Each sister who takes part in the study is given a series of physical and mental tests each year. In this way Snowdon and his associates keep track of the nuns’ health as they age. Through these tests, scrutiny of the records of each sister, and other diagnostic methods, the researchers have been able to draw some conclusions about aging. And, of course, rigorous examination of the brains of those sisters who have died have also revealed significant information.

Among these latter findings was the discovery that many of the women who continued to function adequately in old age had brains with some symptoms characteristic of Alzeimer’s, such as plaques and tangles. But even though they would seem to have had the disease, it did not impede their activities and they were judged to be mentally intact.

Snowdon summarizes this way: “Alzheimer’s is not a yes/no disease. Rather, it is a process – one that evolves over decades and interacts with many other factors.” So the evidence coming from examination of the brain can sometimes prove misleading.

Two factors that Snowdon considers important in the life of the sisters lie outside his scientific testing but deserve attention. The first is spirituality and the second is community. Of spirituality, he says: “My sense is that profound faith, like positive outlook, buffers the sorrows and tragedies that all of us experience.”

Of the second factor, he writes: “The community not only stimulates their minds, celebrates their accomplishments, and shares their aspirations, but also encourages their silences, intimately understands their defeats, and nurtures them when their bodies fail them.”

Ultimately, for Snowdon, the most amazing lesson from this study is that “Alzheimer’s disease is not an inevitable consequence of aging.” This lesson can offer some hope to people who feel anxious as we all await the scientific breakthrough that will free one day free the human family from this terrible affliction.

Richard Griffin