|Marcoantonio Bassetti (1611), Old Nun.
"The participants of the Nun Study included 678 women, all over age 75, with some already exhibiting Alzheimer’s symptoms. Since the sisters at the convent lived similar lifestyles, many factors could immediately be ruled out, providing some experimental control. Over the next few decades the Sisters dutifully took cognitive, memory and physical strength tests: recalling word lists, pulling on weighted cords, and getting physical and mental checkups.
The participating nuns shared written accounts of their lives and personal essays from when they first took their vows with researchers, and even these turned out to provide possible clues to the disease. Indeed, Snowden found that sisters who wrote more complex personal essays in their youth tended not to develop the disease."
In other words, high IQ is a protective factor against Alzheimer's dementia. The smarter novitiates wrote more complex essays and were -- 60 to 80 years later -- less likely to develop dementia. In unguarded moments, neurologists talk about having "brain to burn."
It's good to know that the original Nun Study has inspired other studies:
"Compared to the original Nun Study, the Religious Orders Study is huge: it currently has over 1,350 participants, involves data from over 40 religious orders (including the School Sisters of Notre Dame), and is studied alongside the separate Rush Memory and Aging Project, a study of over 1,850 laypeople. It also includes more diverse group across races and backgrounds."