Comment by lstyls

Not only is that anecdotal, but even if it's true it is correlative in the weakest sense. There are undoubtedly countless other features for which "cultures" (how does one define this concretely btw) with low Alzheimer's rates also are outliers.

Here is a great demonstration of how correlation does not imply causation: http://www.tylervigen.com/spurious-correlations.