If you haven’t heard of Fregoli Syndrome then you are in for a bit of a fun ride (no evil intended). A fictional story should better illustrate this than starting out with the definition.
It so happens that one fine morning you are woken up by your rather angry roommate. He seems to be unhappy about you not putting the bin out. You cooperate and grab it from the kitchen and walk outside to the waiting truck. Even the truck guy looked crossed. As you were returning, scratching your head, still half asleep you feel the truck guy looked somewhat like your friend. You then take a quick shower and go to the nearest shop to get some milk. Your buddy has somehow managed to run to the shop and stood on the other side of the counter as if trying to serve you, with a grumpy face. You vent some steam at him and ask him to stop fooling around. You get slapped and a couple guys drag you outside. A police car arrives and to you utter surprise your roommate again, walks out of the car, cuffs you and shoves you into the back seat.
“The delusion of doubles”, is a rare disorder in which a person holds a delusional belief that different people are in fact a single person who changes appearance or is in disguise. It’s named after a famous actor who was able to change costumes rapidly onstage. The syndrome may be related to a brain lesion and is often of a paranoid nature, with the delusional person believing themselves persecuted by the person they believe is in disguise.
A person with the Fregoli delusion can also inaccurately recall places, objects, and events. This disorder can be explained by “associative nodes”. The associative nodes serve as a biological link of information about other people with a particular familiar face (to the patient). This means that for any face that is similar to a recognizable face to the patient, the patient will recall that face as the person they know.
Traumatic brain injury and antiparkinsonian medications are the leading causes of Fregoli syndrome. The film Anomalisa has several direct and indirect references to Fregoli delusion.
Source: wikipedia.org