Eileen P. Sloan, MD, PhD
Resident in Psychiatry,
University of Toronto,
Capgras syndrome is an atypical psychotic disorder, originally described in 1923 by Jean Marie Joseph Capgras, a French Psychiatrist.1 It is a rare disorder, which probably accounts for the paucity of literature and of systematic study on the topic; a literature search largely produces case reports. It often occurs within the context of other neurological and psychiatric illnesses, such as epilepsy, Parkinson's disease, dementia and schizophrenia.
The characteristic symptom of Capgras syndrome is the delusional belief that other people, usually someone the patient has an emotional relationship with, such as a spouse or child, has been replaced by an impostor, usually one that they consider malevolent. This "double" is physically identical to, but psychologically different from, the replaced relative. The "original" and the "other" always differ in some respect germane to the patient's experience or feelings. The "real" spouse, for example, may have been more affectionate or would have acted differently in a given situation. It seems that the patient does not have difficulty perceiving the subject (e.g. their spouse) but rather can no longer appreciate its emotional significance.