There are degrees of being good at maths you don't see in every other guy you meet in the street... so perhaps you could look at math geniuses if you want a better analogy. John Nash (The main character of A Beautiful Mind) immediately comes to mind, but I'm not sure his schizophrenia had anything to do with his genius.
(However, a very high intelligence often seems to be coupled with poor social performance/mental health problems. I wouldn't think that must be the case with magic, but it would certainly make an interesting complication.)
As for telepathy, to some extent everyone can read people's minds, or at least the emotional part of it :) So perhaps an analogy between maths and telepathy is more appropriate than we'd think, at least as far as the perception of exceptional talents by others goes. Magic in general... I'm not sure.