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Much of this knowledge comes from a single, powerful piece of ongoing research: the aptly named Nun Study, of which Sisters Ada and Rosella are part. Since 1986, University of Kentucky scientist David Snowdon has been studying 678 School Sisters--painstakingly researching their personal and medical histories, testing them for cognitive function and even dissecting their brains after death. Over the years, as he explains in Aging with Grace (Bantam; $24.95), a moving, intensely personal account of his research that arrives in bookstores this week, Snowdon and his colleagues have teased out a series of intriguing--and quite revealing--links between lifestyle and Alzheimer's.
Scientists know that genes can predispose people to Alzheimer's disease. But as described in nearly three dozen scientific papers, Snowdon's study has shown, among other things, that a history of stroke and head trauma can boost your chances of coming down with debilitating symptoms of Alzheimer's later in life; and that a college education and an active intellectual life, on the other hand, may actually protect you from the effects of the disease.
Perhaps the most surprising result of the Nun Study, though, is the discovery that the way we express ourselves in language, even at an early age, can foretell how long we'll live and how vulnerable we'll be to Alzheimer's decades down the line. Indeed, Snowdon's latest finding, scheduled to be announced this week, reinforces that notion. After analyzing short autobiographies of almost 200 nuns, written when they first took holy orders, he found that the sisters who had expressed the most positive emotions in their writing as girls ended up living longest, and that those on the road to Alzheimer's expressed fewer and fewer positive emotions as their mental functions declined.
These findings, like many of Snowdon's earlier conclusions, will undoubtedly spark a lively debate. As laboratory scientists and clinicians are quick to point out, cause and effect are notoriously difficult to tease out of population studies like this one, and exactly what the emotion-Alzheimer's link means has yet to be established. But even hard-nosed lab scientists admit that the Nun Study has helped sharpen the focus of their research. The study has impressed the National Institutes of Health enough that it has provided $5 million in funding over the past decade and a half. "It is," says Dr. Richard Suzman, director of the National Institute on Aging, "a very innovative, pioneering study."
Snowdon wasn't out to change the world when he first began visiting the convent of the School Sisters of Notre Dame on Good Counsel Hill in Mankato, Minn. He wasn't even planning to study Alzheimer's disease. Snowdon was desperately trying to find a research project that would secure his position at the University of Minnesota. He was a young assistant professor of epidemiology at the time--a field he'd been introduced to as a young boy who raised chickens to earn money. "I learned a lot about what it takes to stay healthy from taking care of those chickens," he recalls. "That's what epidemiology is all about--the health of the whole flock."