The comment was made earlier in this discussion that the WT / GB says that some people who claim to be of the anointed may be suffering from a mental illness.
This implies that a mental illness would exclude them from any part in the 144,000. But why? If the 144,000 are chosen so as to relate to the experiences of humans on the earth, surely they would have to have a genuine understanding of mental illness as well. And who better than people who had experienced it first hand!
I'd rather have a heavenly government that understands the complexity of what being human means, than a group of people who think that no one can be right with God if they have been ill.
(Not that it matters really because it is a fairy tale anyway.)