Brains are weirdly complicated; I'm glad you have an explanation that helps some.

I doubt lack of estrogen is the, or even a major, cause of MS, if only because of the demographics: mostly diagnosed between ages 15 and 50, and twice as many women as men. ("A cause" both because lots of things in biology are intertwingled, and because it looks as though MS may be multiple different things grouped as one syndrome.)