Wouldn't all animals be subject to this? At least if they get old enough?
Dunno. I don't think Alzheimer's is a normal part of the aging process. (although I could easily be wrong) If it is a low grade prion disease, it could be acquired by eating infected prey, and predators/scavengers would be more apt to develop the disease than strict vegetarians.
I wonder if a side-by-side comparison of Vishnoy/Jain populations vs neighboring non-vegan or non-vegetarian groups w.r.t. Alzheimer's?
OTHO, predators also have a longer life expectancy than their prey...