The article addresses this question with the example of Greece. The average Greek lives two years longer than the average American, yet they have about one 18th as many Alzheimer’s deaths.
The Mediterranean diet supposedly prevents diabetes, by limiting sugar intake and processed carbs.
Thus the better brain health of Greeks is the diet that prevents diabetes, heart disease and Alzheimers / dementia which is typically caused or exacerbated by both.
In that case, the Greek example is not “they respect the elderly more” but proof the American diet destroys your mind.
Must be the yogurt.