I have a dissociative disorder that I also didn't disclose which might've played a factor in my LSAT (I got a 156), but I highly doubt it. I have a lovely history of crappy standardized test scores.
As for affecting law school, I don't think my "problem" will. I've done well in undergrad, and I feel comfortable under enormous amounts of stress.
Bipolar might be a difference experience, though. . .if you have to take meds that make you jittery or sluggish, that might be something you need to take into account. I'm still not a big fan of how much mental health issues feel like they have some sort of stigma attached. While I'm not ashamed of my situation, I didn't mention it in my applications because none of them asked. If that's the kind of thing I should've mentioned in my personal statement for overcoming adversity, too bad.