Tell Me About Odd Mental Illnesses

Like Truman Show Delusion.

People with Capgras' delusion believe that some person or persons close to them have been replaced with an imposter. They recognize that the "imposter" looks and sounds exactly like who they seem to be, but they are nevertheless convinced that it is not "really" them. This strange delusion appears to arise because Capgras patients (often people with schizophrenia or traumatic brain injury), for whatever reason, have suddenly stopped feeling the subtle warm glow of familiarity and affection that always arises when they used to encounter the close acquaintance. They attempt to rationalize this unsettling absence of subtle affective reaction by concluding that the close acquaintance with whom they are interacting is not "really" who they appear to be -- and they really feel this deep down in their gut.

This video describes and explains this rare phenomenon better than I can:

Thanks. I remember reading about that but the video elaborated a lot more.