Based on the NIH database of grants (CRISP), the study of aging and Alzheimer's disease in the Sisters began in 1991 after he joined the University of Kentucky. Many of the procedures were based on work by Dr. David Wekstein and Dr. William Markesbery. They had, in 1989, started a study of age-associated changes in cognition and function in a group of older adults in Kentucky who had agreed to brain donation at death. Their focus was to understand how changes in the brain could be linked to Alzheimer's disease and other neurological disorders in advanced age. The Nun Study was a natural extension of the ongoing work at the Alzheimer's Disease Center at the Sanders-Brown Center on Aging. Their work continues with the help of over 1,000 older Kentuckians who volunteer to be part of this research effort.
Snowdon's book on the Nun study, Aging with Grace: What the Nun Study Teaches Us About Leading Longer, Healthier, and More Meaningful Lives, won a Christopher Award in 2002.