Brain Syndrome Can Make Owners Think Pets Are Impostors

Herzog, Harold, "Brain Syndrome Can Make Owners Think Pets Are Impostors" (2018). 'Animals and Us' Blog Posts. 103, Apr 25, 2018. https://animalstudiesrepository.org/aniubpos/103

Mary was 40 years old when she became convinced that Sarah, her 9 year old daughter, was an impostor.  The real Sarah, she told relatives, had been taken away and placed into a foster home. She claimed social workers had replaced her actual child with an identical-looking impostor.  Mary was so convinced of this substitution that she would sometimes refuse to pick her daughter up at school. Mary would scream to the teachers, “Give me my real daughter back, I know what you have done!”
To no avail, her family and health care providers tried to convince Mary that no substitution had occurred, that Sarah was indeed her real daughter.  But even after Mary was treated with risperiodone, a powerful anti-psychotic drug, she held on to the delusion. The local Department of Social Services became concerned about her ability to raise a child. And when it became apparent that Mary could no longer provide care for the daughter who she believed was an impostor, they successfully sought legal guardianship for Sarah. At one point during the hearing, Sarah told the court, “I love my mother, except when she doesn’t believe I’m me.”

As described in an article by Drs. Jeremy Matuszak and Matthew Parra in the journal Psychiatric Times, Mary was suffering from Capgras Syndrome. This is a rare variant of a group of neuropsychiatric conditions called delusional misidentification disorders.  First identified in 1923 by the French psychiatrists Joseph Capgras and Reboul-Lachaux, individuals with the Capgras delusion come to believe that a person they know has been replaced by an identical-looking impostor. Usually the target of the delusion is a family member or a loved one. In Mary’s case, it was her young daughter.

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What Causes Animal Capgras Delusions?

I admit that nine cases is a small sample, but some interesting patterns did emerge among this group of patients. For example, twice as many women as men thought they were living with impostor animals.  And, as group, the patients tended to be on the old side. Six of eight individuals were over 50, and half were in their late 60’s or older. While only two of the patients had suffered identifiable brain damage, nearly all the patients had been diagnosed with a functional psychosis, usually a form of schizophrenia.  Finally, all seven of the patients which there was information on treatments were given anti-psychotic drugs. In nearly all of these cases, their pet impostor delusions diminished, and in several cases, they seemed to have disappeared.

Speculations about the causes of Capras syndrome abound. The some researchers argue that impostor delusions are a way of subconsciously dealing with love-hate conflicts. V. S. Ramachandran believes that imposter delusions result from disconnections between emotional and face recognition centers in the brain.  Others argue it is usually the result of degenerative diseases such as Alzheimer’s and Lewy body disease. Indeed, impostor delusions have been associated with a wide array of conditions including psychiatric disorders, strokes, tumors, epilepsy, and even vitamin deficiencies and drug use.