Capgras Delusion

**Capgras delusion** is a psychiatric disorder in which a person holds a delusion that a friend, spouse, parent, or other close family member (or pet) has been replaced by an identical impostor. It is named after Joseph Capgras (1873–1950), a French psychiatrist.

The Capgras delusion is classified as a delusional misidentification syndrome, a class of delusional beliefs that involves the misidentification of people, places, or objects. It can occur in acute, transient, or chronic forms. Cases in which patients hold the belief that time has been "warped" or "substituted" have also been reported.

The delusion most commonly occurs in individuals diagnosed with paranoid schizophrenia but has also been seen in brain injury, dementia with Lewy bodies, and other dementia. It presents often in individuals with a neurodegenerative disease, particularly at an older age. It has also been reported as occurring in association with diabetes, hypothyroidism, and migraine attacks. In one isolated case, the Capgras delusion was temporarily induced in a healthy subject by the drug ketamine. It occurs more frequently in females, with a female to male ratio of approximately 3 to 2.

## The Beginning

In 1932, French psychiatrist Joseph Capgras and his intern Jean
Reboul-Lachaux described Madame M., who insisted that her husband was
actually an impostor who looked exactly like him. She did not see just
one impostor husband, but at least 80 different ones over the course of
ten years. In fact, doppelgangers
 replaced many of the people in Madame M.'s life, including her
children, who she believed had been abducted and substituted with
identical babies.
Who were these faux humans and where were they coming from? It turns
out they were actually the individuals themselves — her husband, her
children — but they didn't feel familiar to Madame M., even though she
could recognize that they looked the same.

## The Capgras Delusion

Madame M. had the Capgras Delusion, which is the belief that people,
often loved ones, are not who they appear to be. Instead, people who
experience the Capgras Delusion believe that these people have been
substituted by doppelgangers or even robots and aliens who have crept
into the flesh of unwitting humans. The delusion can also extend to
animals and objects. For example, someone with Capgras Delusion might
believe that their favorite hammer has been replaced by an exact
duplicate.

These beliefs can be incredibly unsettling. Madame M. believed that
her true husband had been murdered, and filed divorce from her
"replacement" husband. Alan Davies
 lost all affection for his wife, calling her "Christine Two" to
differentiate her from his "real" wife, "Christine One." But not all
responses to the Capgras Delusion are negative. Another unnamed individual,
 though bewildered by the appearance of who he felt were a fake wife and
 children, never appeared agitated or angry toward them.

## Causes of the Capgras Delusion

The Capgras Delusion can arise in many settings. For example, in
someone with schizophrenia, Alzheimer's, or another cognitive disorder,
the Capgras Delusion may be one of several symptoms. It can also develop
 in someone who sustains brain damage, like from a stroke or carbon monoxide poisoning. The delusion itself can be temporary or permanent.

Based on studies involving individuals with very specific brain
lesions, the main brain areas thought to be involved in Capgras Delusion
 are the inferotemporal cortex, which aids in facial recognition, and the limbic system, which is responsible for emotions and memory.