The deliusion which involves replacement of a familiar person by someone else is -

Ans. is 'a' i.e., Capgras syndrome The delusional misidentification syndromeso DSM is characterized by misidentification delusions of other or self. Four main syndromes are differentiated : -Capgras syndrome (Delusion of double) : - Patient falsely sees a familiar person as a complete stranger who is imposting on him as a familiar person.Fregoli syndrome (illusion de fregoli) : - The patient falsely identifies stranger as familiar person.Syndrome of subjective double : - The patients own self is perceived as being replaced by a double.Syndrome of intermetamorphosis ; - A false belief that a person can transform into another person.o These syndrome most commonly appear in schizophrenia. Other causes axe Alzheimer syndrome, head injuries, and delusional disorders.