He had something-I-can't-pronounce-or-really-remember syndrome. I'm not medicaltitian, so I don't worry too much about the why's. They did explain it though (in the sense that they said he had X disease, and this means Y happens).
You can't pronounce mirror?
Part of his disease was a syndrome that caused him to analyze people, and then reflect what he saw. Apparently with really good accuracy. I assume this syndrome is real but it's probably been exaggerated incredibly for the episode.