I believe it depends on how the so called disability affects one and the impact on job performance; weather to disclose or not. And yes, your prospects of landing a job are greater wo telling anyone... unfortunately.

I would also like to add that in many professions physical disability is not looked upon as a negative at all. They are looking for brain power. Mental disability is much more difficult to explain without the potential employee thinking you are crazy from day one. This because MI is so stigmatized by the society. People "fear" the unknown.

Good luck if you are looking for a job