I agree- do whatever fires up your passion - either way it involves research, grant writing, teams and lab time.

Personally, I think neuroscience is one of the hottest fields in science/medicine. There are so many sub specialties, only one of which is MS or other neuro-degenerative disorders. There is a vast amount of unknown just waiting to be explored and conquered. Sort of like where cancer research was in the mid 70s.

IF (and that is a mighty big 2 letter word) you end up with MS it would give you the added "connection" to research. But the choice is yours. You still have time to choose, and could always change specialties later if you wanted. I don't think MS would get in your way too much, but each person's MS is unique to them.

Good luck and good for you!