The article mentions Capgras syndrome - one of the most interesting mental conditions out there. There's a really good novel by Richard Powers called The Echo Maker, where the main character chronically suffers from Capgras after a traumatic brain injury. This is a very rare but real phenomena where the person accurately remembers most everybody that they knew prior to an injury, but they are irrevocably convinced that the one person they were closest to is an imposter put into their lives by the government. No amount of evidence can change their mind. That book is one of my favorite reads, and it has other true case histories of other similarly bizarre brain conditions woven into the story.