It's funny... He's saying that because carnivores get Alzheimer's and herbivores do not, meat causes Alzheimer's. You could use similar logic to say, carnivores get Alzheimer's and herbivores do not, humans get Alzheimer's, therefore, humans are carnivores. Both statements are useless unless you use them as a basis for a study. The fact that he's using this silly shit to direct people towards a healthier diet is ridiculous. Srs, I have second hand embarrassment for this guy.
For this to be at all relevant... You would have to compare carnivores put herbivorous diets, herbivores put on carnivorous diets. And omnivores! Why does he not mention omnivores? Le sigh.