This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
The deliusion which involves replacement of a familiar person by someone else is ? 
Select and explain. 
A. Capgras syndrome, B. Cotard syndrome, C. Othello syndrome, D. None
A: Capgras syndrome
Answer: A: Capgras syndrome 
Explanation: Ans. is 'a' i.e., Capgras syndrome 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 impoing 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. These syndrome most commonly appear in schizophrenia. Other causes are Alzheimer syndrome, head injuries, and delusional disorders.