Alzheimer’s disease may be like hardening of the arteries, resulting from a lifelong biological deterioration that becomes apparent only when people are older, say authors of a study of nuns who are donating their brains to science.
The study analyzed nuns’ youthful writings and found that those women who showed low linguistic ability when they were in their 20s had a much higher risk of Alzheimer’s when they were elderly.
The findings could indicate that Alzheimer’s impairs language ability when people are young, the researchers said. On the other hand, greater linguistic ability early in life might indicate a healthy brain resistant to Alzheimer’s later on.
“It’s a chicken-or-an-egg thing at this point,” said the lead researcher, David A. Snowdon, an associate professor of preventive medicine at the University of Kentucky. The findings are published in today’s issue of the Journal of the American Medical Assn.
The researchers studied the autobiographies of 104 nuns from the School Sisters of Notre Dame. The order’s 678 nuns have agreed to donate their brains for the federally funded research.
The women wrote one-page accounts of their lives for the order’s archives just before taking their vows, at an average age of 22.
Scientists autopsied the brains of 25 nuns who died, 10 of whom had Alzheimer’s. Those who had low linguistic ability when young had abundant neurofibrillary tangles, the lesions of Alzheimer’s disease, when they were old.
Ninety percent of the nuns who developed Alzheimer’s disease had shown a low linguistic ability in their autobiographies, compared with only 13% among those who did not have Alzheimer’s, the researchers said.
Snowdon said he has no reason to believe the findings would be different in men.
Alzheimer’s disease, which slowly robs victims of their memories, reasoning powers and ability to function, afflicts an estimated 4 million Americans, and 100,000 die of it yearly.