Thank you Lauren for a well-researched article. My first response to this is to suggest that the food we eat today sis so compromised it's not funny.
Just the other day I wrote about a South American billionaire duo (brothers) that has infiltrated its way into Australia's back door through devious means They operate under a variety of names. When you have to do that, you can bet your bottom dollar that what they sell of less than healthy...so we're talking meat and fish here, staples for many of us. How to avoid them? Be wealthy enough to say no to their crappy offerings. Go where bidynamic farmers sell.
Also, as far as dementia is concerned, I think getting rid of every skerrick of factory food possible would be my first suggestion to stave off dementia.
And then there's the ketogenic diet...this article very articulately covers all your concerns. https://www.dietdoctor.com/low-carb/benefits/alzheimers