This CBS 60 Minutes story from 2014 profiling "super seniors" those that are above the age of 90 and how much original hypotheses about aging, and age related dementia have been debunked. https://www.youtube.com/watch?v=wqKfL3z5yM4
Their findings are all over the map, They found that the original hypotheses that brain plaques cause dementia was false. They found that moderate consumption of alcohol is actually beneficial in prolonging life and what is counter intuitive they found that being too thin and having to low of blood pressure causes dementia. meaning decades of medical science is thrown out the window including psychology of you do X on a cog test you have Y diagnosis. Peg is round so it has to go in the round whole when the brain is anything but and shows how much science doesn't have a clue as to how the brain works.
Another 60 minutes story, this time from October 2021 profiles Tony Bennett's fight with Alzheimer's where even his neurologist cannot explain how the brain works and that when the music to his songs starts, Tony is able to preform them without skipping a beat even though he cannot remember his own actions.