David Snowdon at the University of Kentucky, Lexington, and colleagues have for over a decade been studying aging and cognition in a population exposed to the bare minimum of environmental "noise": 678 nuns aged 75 and over who live at convents around the country. The researchers tapped a unique resource, short autobiographical sketches written by 180 of the nuns when they took their vows more than 60 years ago. The writings were analyzed according to two measures: "idea density," or speech content gauged by the number of ideas expressed per 10 words in a sentence, and grammatical complexity.

Between 1991 and last March, 58 nuns who had written bios died, Snowdon reported at a recent meeting in Paris sponsored by the IPSEN Foundation for research on medical therapies. The median age at death for nuns who had expressed low idea density was 81.7; for the high-density nuns, it was 88.5.

Because the nuns from early adulthood were cloistered from hazards such as poverty, drugs, and poor health care, the finding, says Snowdon, suggests that the differential could have "more to do with linguistic and cognitive abilities ... than to [adult] lifestyle and environmental risk factors." The researchers found no link between mortality and complex grammar, suggesting that longevity is related more to "cognitive abilities" than "linguistic proficiency," the authors write.

Deeper thinking nuns may have richer, more redundant, less error-prone neuronal structures and thus be less susceptible to life-shortening dementia, Snowdon speculates. Indeed, of 24 brains examined post-mortem so far, he says, Alzheimer's lesions were about 10 times as prevalent in the low-octane thinkers as in the women who possessed a high density of ideas.

This is "an enormously creative, interesting, and important study," says Richard Suzman, chief of demography and population epidemiology at the National Institute on Aging. But, he cautions, "it cries out for replication."