Delusion of doubles is found in

CAPGRAS' SYNDROME (THE DELUSION OF DOUBLES) Capgras' syndrome is a syndrome that is closely related to delusional disorders and is characterised by a delusional conviction that other persons in the environment are not their real selves but are their own doubles. It is one of the several delusional misidentification syndromes, of which there are four types described: 1. Typical Capgras' syndrome ( Illusion des sosies): Here the patient sees a familiar person as a complete stranger who is imposing on him as a familiar person. 2. Illusion de Fregoli: The patient falsely identifies stranger(s) as a familiar person(s). 3. Syndrome of subjective doubles: The patient's own self is perceived as being replaced by a double. 4. Intermetamorphosis: Here the patient's misidentification is complete and the patient misidentifies not only the 'external appearance' (as in the previous three types) but also the complete personality. Ref: A Sho Textbook of Psychiatry, Niraj Ahuja, 7th Edition, pg. no. 87