The 61 surviving nuns recently completed their last round of intellectual and physical tests for the Nun Study, one of the world's most comprehensive neurological research projects.
One final sacrifice remains: When they die, their brains will be taken for further study, joining a collection of hundreds of other brains donated by the the nuns who died before them.
Sister Treanor, a 93-year-old former school principal who is one of the last of the volunteers at a Wilton convent, looks at her participation as service, not sacrifice.
"I've tried to do good while I'm alive, and I liked the idea that I could do something good after death," she said.
With the modesty of their calling, the nuns attribute the study's success to researcher Dr. David Snowdon, downplaying their own countless hours of interviews and testing over the decades.
"I never minded having my brain checked out. It kept me out of trouble," said 96-year-old Sister Antoine Daniel.
Researchers say Snowdon's work already has produced interesting results, including a finding that people who challenge themselves intellectually can apparently delay or prevent the onset of Alzheimer's symptoms.
Snowdon's work also suggests that in people predisposed to Alzheimer's, a stroke or head trauma can speed the disease's progression
- an argument for wearing seat belts, helmets and other protective gear.
He also has researched the levels of folic acid in the blood of deceased nuns with and without dementia; why nuns with positive attitudes and creative verbal skills tend to live longer than their glass-half-empty peers; and other questions.
"We'll continue to learn from the sisters for many, many years to come," Snowdon said.
Snowdon was a nervous young epidemiology professor at the University of Minnesota when he approached the first group of nuns in 1986 at the School Sisters of Notre Dame order in Mankato, Minn.
Although Pope Pius XII had declared in 1956 that donating organs was acceptable in the Roman Catholic faith, asking nuns to leave their brains to science for post-mortem testing was a delicate task. That was especially true for Snowdon, who had attended Catholic school and still viewed nuns with a mix of reverence and intimidation.
Yet getting them to donate their brains was critical because the only indisputable diagnosis of Alzheimer's comes from examining a patient's brain after death.
