You could reasonably conclude that this list would be similar to the highest life expectancy list. However, Japan is #58 with a rate of 4.23 Is it genetics, diet, environment, or difference in reporting?
Dairy consumption has been linked to alzheimers (as well as to osteoporosis) so if you look at the world wide consumption of dairy products you'll see that these countries are on top. And maybe that's why Japan is missing from your list too?
As you mention in the caveats, the rates are age-standardized, meaning that the crude rates are adjusted so that the different age profiles of countries don't affect the data. As for why Japan has such low numbers, I guess that, apart from genetics, diet probably plays a significant role, as I remember reading that Japanese-Americans have a much higher incidence of Alzheimer's than the Japanese.