I wanted to joke that extra crispy may then actually be health food, but I won't. What I will say it that correlation does not imply causation.
Except for liquids, I chew all foods. Some are easy, others require more effort (and then I change carnecerias). It is overly simplistic to imply a force threshold causes a multi-faceted disease The brain is a marvelously complex organ, increasingly so at the synaptic and molecular levels, with multiple redundancies and feedback loops. Will eating better improve your health? Probably, but don't read too much into it.
Would that Alzheimer's were so simple to avoid... but thanks for sharing the video.