In 1996, a 22-year-old American woman suffered head trauma due to a car accident. Two years after that, she began to suffer seizures. Unfortunate, yes, but not too out of the ordinary. In 2004, however, she was brought to the psychiatric ward of a Pittsburgh hospital, presenting with delusions that strangers around her were actually her friends and family members in disguise. The woman told the hospital staff, for example, that another patient was her boyfriend and that a nearby social worker was actually her sister and that her mother was posing as one of the nurses.
The woman was diagnosed with a rare condition called Fregoli syndrome, named after a turn-of-the-century Italian actor who was famed for his quick costume and character changes. Sufferers of the disorder imagine that the people in their world are all the same person or handful of persons posing in disguises.