Misidentification syndromes at the interface of neurology and psychiatry

As neurologists, sometimes we deal with special « delusions ».
Misidentification syndromes are rare neurologic conditions in which the patient attributes a wrong identity (a sort of hypo-identification) to people (Capgras syndrome or doubles’ illusion), to places (reduplicative amnesia), or believes that the physical appearance of a person changed into that of another (Fregoli syndrome), this last condition corresponds to a sort of hyper-identification. A parallelism can be traced between the Capgras syndrome and somatoparaphrenia (a right hemisphere syndrome). The patient with somatoparaphrenia believes that his or her paralyzed left arm belongs to another person.
The patient with the Capgras syndrome believes that his spouse has been replaced by another person or an alien. So, even if her physical aspect is the usual, inside there is an impostor.
Despite all plausible evidence, there is no way to persuade him that he is wrong. This situation well reminds the 1957 American science fiction horror movie « the invasion of the body snatchers », a cornerstone of extraterrestrial invasions in movies. The patient does not understand that no-one believes him on the false identities of people.
The patient with reduplicative amnesia believes that his house, despite a normal aspect, has been replaced by another location.
More types of misidentification can coexist in the same patient.
All these conditions are at the interface between neurology and psychiatry as they can manifest either with neurologic disease (stroke, subdural hematoma, Alzheimer’s disease, Lewy-body disease, drug intoxication, brain trauma, Parkinson’s disease, Fahr’ disease, levodopa-induced psychosis, epilepsy) or psychiatric disease without brain lesions (such as paranoia, schizophrenia, mania, and dissociative disorders).
Capgras syndrome and reduplicative amnesia manifest after frontal parietal, occipito-parietal, and thalamic lesions. The neural mechanisms underlying the dissociation between appearance and identity of the bodies remain speculative. However, it points to the existence of different cognitive and emotional networks for recognition (or memory) of faces and bodi, networks having different neural substrates or hemispheric dominance.
If you think that your spouse has been replaced by an alien or that your house is another place consult us as something could be wrong in specific regions of your brain.

Ce contenu a été publié dans Cognition and Behavior, Lewy Body Disease, Parkinson Disease, Psychiatry. Vous pouvez le mettre en favoris avec ce permalien.

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