I used to do research like that too, until i realized that those "experts" have many different opinions. So, i went to the source and read the actual studies with real data, which is very clear and consistent with the official notions.
There can't be any study that say that carbohydrates are deadly in the long term for the brain, it's like saying that cellulose is poison for bovines... it's just the correct fuel, our metabolism is sugar based. In fact, if you go check the studies about centenaries in the blue zones, the only thing they all have in common is a basically vegan diet made of 90% carbs.
Our metabolism runs 50% on carbs, 50% on fat, brain actually prefers fats (even healthy person produces ketones in smaller amounts and most of them go to the brain)
The studies in okinawa was made in 1945 the year after the world war2 where there was shortage of pigs, after the war when the population was still halved the pig population skyrocketed, it aint vegan per say, I advise around 30% meat 70% veggies without carbs.
You still didnt watch any of the links that I sent you...