Volume 7 Issue 11 November, 2017
Capgras Syndrome was described by Capgras and Rebeul-Lachaux in 1923.It is also called illusion des sosies, and is one of the most colorful syndromes in neuropsychiatry. It describes a phenomenon whereby a patient believes that someone, usually a loved one or somebody with whom the patient has close emotional ties has been replaced by an identical looking imposter. The other misidentification syndromes that have been described in Psychiatry include Fregoli’s Syndrome, Syndrome of intermetamorphosis and the syndrome of subjective doubles.
Capgras Syndrome is a delusional misidentification syndrome that represents the concept of doubles has been mentioned in many different cultures that have myths involving doubles. The earliest descriptions are in Greek mythology where the God Zeus in his desire to have sexual intercourse with Alceme assumed an identical form of her husband Amphitryon and tricked her into having a sexual intercourse with him. One of the best descriptions of the syndrome in contemporary literature has been given in the novel ‘Possessed’ by Dostoyevsky which describes the non-recognition by one of the characters of her husband.
Capgras syndrome forms an interface between Psychiatry and Neurology as around 40% of cases show an evidence of an organic disorder. Other conditions wherein an organic etiology is more obvious are déjà-vu, jamai-vu, and out of body experiences associated with temporal lobe disturbance and autoscopy. Neuropsychologically these disorders can be traced to involvement of the watershed areas of the tempero-parieto-occipital region which has been termed the multimodal association area.
One of the explanations of Capgras syndrome is that there are apparently two components for the recognition of a familiar face and the related semantic information and the other being limbic mediated emotional arousal. A dissociation between these two systems may explain the origin of Capgras delusion. There are two pathways of the visual system, the ventral route carries information from the visual centre to the temporal lobes which is preserved in Capgras syndrome but the dorsal visual route that is responsible for giving an emotional valence is damaged. Hence the patient is able to identify the face of a person but the emotional arousal fails to occur. The only way the patient can make sense of the absence of emotional arousal is to form the belief that the person he is looking at is an imposter. One of the differential diagnoses is Prosopagnosia or face blindness which results from bilateral lesions of the inferior temporal lobes.
Capgras syndrome has been reported with various organic disorders including right cerebral dysfunction, subarachnoid hemorrhage, head injury, temporal lobe dysfunction, pseudohypoparathyroidism, myxoedema, epilepsy and many other conditions. Since the evidence suggests that over a third of cases of Capgras delusion have an organic etiology, it has been suggested that in case of delusional misidentification there should be a thorough search for organic pathology.
Dr. Najla Eiman, consultant Psychiatrist, AIMS, Bellur
