this is more or less what i have heard. i hadn't heard it in context of diet, but i could see that. personality swings as a precursor to dementia is what i've read., with dementia in this sense being a bit of a catchall for cognitive decline.

I think it’s trauma. There was a family tragedy and they divorced after 45 years of marriage and both of them are acting very out of character. Their diets and health are rather good.