mdpi.com/1422-0067/25/1/590 This article is a bit beyond my weary synapses, but it gives a good overview of the recent (2023) knowledge on what vitamin B12 deficiency does to the brain.
As far as I've gathered as well as stopping myelin sheath forming properly, lack of B12 stops the brain's dustbin men working and stops synapses connecting. Which all fits with my memory recall trouble, the embarrassing kind of I know I know you, but I don't know how, or what your name is situation, especially when meeting people in a different place, and random memory revival since self injecting. If you don't remember something mostly you don't know you've forgotten it.
I'm sure CluB-12 would love an excuse for an Italian jolly!!
But I guess the main thing is it highlights there is still plenty to find out.
It all rather morbidly makes me wonder where I can donate my brain to help the cause, when I shuffle off.
It also mentions the combination of B1, B2, B3, B6 with B12 to tackle oxidative stress in the brain.