Eliza Jane makes a great case for many of the first things that popped into my head upon reading your post, BRN. Insanely vague indeed. Quite sure lawyers rub their hands over being able to get their chompers into such vague language. Gives 'em so much to work with from all sorts of angles(!) And what of those with anger management issues? Forgetful natures? Minds that are elsewhere because they can't leave their personal life at the workplace door? Just plain bad and jaded attitudes? These sorts of things come from their brains, and therefore are mental issues. Even if one cannot be diagnosed with with these things (ie. "illness" if that is the exact word, and alright, it probably is. Still...) Let's face it -- someone with a bad and jaded attitude is affected by this in the performance of their job EVERY SINGLE DAY. No "could" about it.

First thing I'd look into is if the question is even legal.

Personal viewpoint: Until it becomes relevant and necessary, I won't answer certain things. For instance, social security number. They ask on every single application, and it's none of their damn business! There are actually very few instances where one is legally compelled to give it. Doesn't stop them from asking though. Once it actually becomes relevant and necessary, I give the information. But I don't need that info floating around for no good (or even legal) reason, you know?

Sorry to jump in on this, as I'm not in the medical field (and have not even been posting lately), but it just really fries my bacon that you should even have to deal with such nonsense.