People with Capgras Syndrome Think Their Family or Friends Are Imposters

When you're high, that guy sitting across from you, who used to be your friend, may all of a sudden look slightly different. Your brain can attribute the change in your friend's appearance to a number of factors.

You may be self-aware, and realize that your current state has slightly altered your perception, and it's not your friend that looks different, but rather, your perception of him.

You could also decide this person has been replaced with an imposter. This can happen in the absence of drugs, and last much longer than a bad trip.

It can occur if you're suffering from schizophrenia or certain brain trauma (as well as methamphetamine abuse). In this case, you may be suffering from Capgras syndrome.

What is Capgras Syndrome?

Named after Joseph Capgras, the French doctor who discovered the disorder, the affected person thinks one or more people in their life have been replaced with an imposter. The syndrome, also known as the Capgras Delusion, is rare, but presents itself more often in those suffering from schizophrenia14:1%3C48::AID-GPS891%3E3.0.CO;2-0/abstract).

I spoke to Dr. Deepak D'Souza, a friend and professor of psychiatry at Yale, to learn more about Capgras syndrome. D'Souza explained Capgras as an issue of reasoning. Someone suffering from schizophrenia may perceive a loved one to look slightly different, or act slightly different, and instead of adapting their current understanding of this person, they attribute the change to the more radical notion that they've been replaced.

This "false" reasoning is usually associated with schizophrenia, but can also be induced through drug use or trauma to the brain.

As D'Souza explained to me, "Think of the brain as a system of highways, you could have an accident on a bridge in New Haven that manifests itself as a traffic jam in Bridgeport. [Note: We've both lived in Connecticut.] And if you're only looking in Bridgeport, you may think that's where the problem is. Everything about the brain is about a network, everything is connected."

In this case, a patient had Capgras syndrome induced after head trauma received in a car crash.

Theories of causation

The causes of the delusions in Capgras syndrome are not yet entirely clear, nor is it attributed to a specific region of the brain. A study of 38 Capgras syndrome patients concluded the syndrome is often associated with neurodegenerative disease. The study also showed Capgras can be present without neurodegenerative disease, as a result of "psychiatric disease, cerebrovascular event, or illicit drug use," specifically methamphetamine abuse.

While the two most popular approaches to defining Capgras come from psychiatry and neurology, they are not the only attempted explanations. One theory from a psychiatry journal in Japan, takes a more otherworldly approach to the syndrome. The author suggests Capgras syndrome is an issue of metaphysicality, and those suffering from it may actually exist in another dimension with their imposters, separate from the world that the rest of us inhabit. (While this plunge into another dimension seems unlikely, it hasn't been explicitly ruled out.)

A Difficulty in Diagnosis

Diagnosing a delusion is not as simple as diagnoses of physical illnesses. "If someone has a cough, most people will agree what they think a cough is. You either have it or you don't have it," D'Souza said.

Delusions are much more complicated. The latest Diagnostic and Statistical Manual of Mental Disorders (DSM 5) defines delusions as "fixed beliefs not amenable to change in light of conflicting evidence." This would place many sports fans and otherwise mentally healthy individuals as clinically delusional. The DSM 5 seems to acknowledge this by admitting "the distinction between a delusion and a strongly held idea is sometimes difficult to make and depends in part on the degree of conviction with which the belief is held despite clear or reasonable contradictory evidence regarding its veracity."

In addition, delusions shared within a culture are not considered delusions. This explains why a student in Catholic school claiming God spoke to him would be considered a pious young man, not delusional.

This difficulty in diagnosis could explain the limited amount of cases of Capgras reported. For example, this case report shows a patient developing Capgras syndrome after a multiple sclerosis relapse. After she attacked her husband, thinking he was an imposter, he brought her to the ER. If she'd been arrested instead, it's unclear whether the nuance of Capgras would've been recorded, or just considered to be suffering from some other delusion.

Ketamine Research

When I initially contacted D'Souza to see if he was familiar with Capgras at all, it turned out he'd encountered a case of Capgras in his own research lab.

To observe and research the mechanisms of schizophrenia, researchers like D'Souza can't rely on traditional experimentation methods. Conceptually, designing research methods for physical diseases like diabetes and cancer is simpler: Using an animal such as a rat or a pig, you can simulate these diseases, take notes, and test treatments on the animal before moving to human trials. However, it's much more difficult to induce psychosis in a monkey and then ask it to fill out a questionnaire.

A study co-authored by D'Souza yielded what is the first reported case of Capgras temporarily induced in a healthy subject. A 26-year-old graduate student, under a supervised dose of ketamine, recalled experienced a state where those around her seemed to be replaced with near-identical imposters, who were older and a bit heavier when they left and re-entered the room. She reported time both slowing down and speeding up, her anxiety increasing, and energy decreasing.

This experience seems to be clinical description of the slang term, a K-hole, where the user is dissociated from themselves and the space-time continuum. The graduate student also reported her own image in the mirror did not appear to be herself, based on the way this person sounded, looked, and how they were reacting to the situation.

The goal of D'Souza's research is to use ketamine to induce schizophrenia-like symptoms in healthy patients, to then study how to potentially curb those symptoms. "The idea is to administer drugs to induce symptoms that resemble the symptoms of schizophrenia temporarily," he said. "If we have a drug that in the laboratory can provoke symptoms that resemble the symptoms of schizophrenia, in a healthy person, we can try find a drug that can block those effects."

This experiment and accidental simulation of Capgras is a step towards better understanding the syndrome. But still, there are no clear effective therapies or treatments for Capgras syndrome today.

It's difficult to walk away with a substantial grasp on the Capgras Delusion, given our limited knowledge of its genesis and lack of treatment available. It's motivation to continue and expand efforts in schizophrenia research. Gaining understanding of the cause and effects of the Capgras could help in comprehending and treating schizophrenia, and vice versa.

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