IntroductionCapgras illusion is one of the rarest and most colorful syndromes in neurology. The patient cannot recognize the faces of his loved ones and calls them “imposters”. They claim that the person “looks like” or is “the same” as someone they know, while continuing to believe that they are two different individuals. The delusional belief is stronger when the putative imposter is present [2]. Capgras delusion is classified as a delusional misidentification syndrome, a class of beliefs in which patients have delusional beliefs that involve misidentification of people, places, or objects. Delirium is mainly common in patients diagnosed with neurodegenerative diseases; such as Alzheimer's disease (2% - 30%) [8], schizophrenia (15%) [9] and dementia. It has also been observed in patients with brain damage causing damage, suggesting that the syndrome has an organic basis.HistoryCapgras syndrome (CS) is named after Joseph Capgras (1873-1950), a French psychiatrist. He first described the disorder in the case of a French woman who complained that correspondent "doubles" had taken the place of her husband and other people she knew. Capgras and Reboul-Lachaux first called the syndrome "l'illusion des sosieaux", which translates to "the illusion of lookalikes" [1]. Capgras syndrome was initially considered a simple psychiatric disorder. Such delusions of doubles were considered one of the various symptoms of schizophrenia and a purely female disorder [2]. Most of the explanations initially proposed were psychoanalytic in nature. Starting in the 1980s, neurologists began analyzing coexisting organic brain lesions that were originally thought to be unrelated to symptoms...... middle of article ......atic without Autonomic responses to familiar faces: differential components of covert face recognition in a case of Capgras delusion. Cognitive Neuropsychiatry 5, 255-269.[18] Tranel, D., Damasio, AR, 1985. Knowledge without consciousness: an autonomous index of facial recognition by prosopagnosics. Science 228, 1453-1454.[19]Tranel, D., Damasio, H., Damasio, AR, 1995. Double dissociation between open and covert recognition. Journal of Cognitive Neuroscience 7, 425-432.[20] Reid, I., Young, AW, Hellewell, DJ, 1993. Speech recognition impairment in a blind Capgras patient. Behavioral Neurology 6, 225-228.[21] Shah, NJ, Marshall, JC, Zafiris, O., Schwab, A., Zilles, K., Markowitsch, HJ, Fink, GR, 2001. Neural correlates of person familiarity: a magnetic resonance imaging study functional with clinical implications. Brain 124, 804–815.