TIME.com: Health -- The Nun Study Because the records were relatively standardized, Snowdon could extend his study of aging far beyond the few years in late life that such studies traditionally cover. Most precious of all were the autobiographies written by each sister on her entry into the order. They were full of basic information about where the sisters were born, who their parents and siblings were, and why each one decided to join the order. With these documents, moreover, Snowdon now had an objective measure of the sisters' cognitive abilities while they were still young and in their prime. An epidemiologist could not have designed a better way to evaluate them across time. "For many years," says the National Institute's Suzman, "we had an inadequate sense of how connected late-life health, function and cognition were to early life. But in the past decade, spurred by the Nun Study, there is a growing appreciation for that connectedness."