In the book I referenced earlier, the scientist likens it to 36 or more holes in the roof which is why a pill won't work because it targets only one hole. It does nothing to solve the overall problem which is why there hasn't been any Alzheimer's drug in decades and the few we have aren't very effective.
Diet, supplements, exercise physical and mental all help plug up the holes and protect the brain. Definitely an all encompassing approach is needed.
The biggest obstacle holding us back according to the researchers is the grant money is only being awarded to drug testers who are continuously failing and refused to what seems to be consistently working which is the multiple treatments approach.