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5 Rare and Unusual Psychological Syndromes

by Althea Ocomen

1. Capgras Syndrome

During the trial of Clay Shaw in the movie JFK, a prosecution witness stated that he was present when Shaw and David Ferrie discussed strategies for the president’s assassination. On cross-examination, Shaw’s lawyer discredited the witness by asking the following questions (I paraphrase):

Lawyer: Isn’t it true that you routinely fingerprint your daughter when she leaves for college?

Witness: Yes.

Lawyer: And isn’t it also true that you fingerprint her again upon her return from college?

Witness: Yes, I do.

Lawyer: Why do you do that?

Witness: Because I want to make sure that the daughter I get back is the same daughter that I sent off to college.

This bizarre exchange happened at the trial of Clay Shaw, as the witness displayed behavior similar to patients with Capgras Syndrome. Like the characters in Invasion of the Body Snatchers, people with this condition become convinced that imposters have replaced one or more people that they are familiar with. A French psychiatrist, Joseph Capgras, first identified this delusion in 1923, when a patient insisted that her husband and several acquaintances had been replaced by exact replicas.

2. The Fregoli Delusion

The Fregoli delusion is the belief that different people are the same person. For example, a man in his early twenties fell in love with a woman who turned him down, then came to believe that all of his Facebook friends were this woman in disguise. This led him to think that her many disguises and impersonations of different people meant that she was as obsessed with him as he was with her. It doesn’t take much analysis to see the young man’s delusion as a primitive ego defense. 

3. The Syndrome of Subjective Doubles

The Sixth Day and The Stepford Wives are two movies that dramatize the plight of characters who must contend with doppelgängers or exact duplicates of themselves who have separate lives and different personalities. In literary fiction, The Strange Case of Dr. Jekyll and Mr. Hyde is synonymous with the concept of the “evil twin.” 

A person who has succumbed to the syndrome of subjective doubles believes that he or she has an exact double, but one with a different personality or attitude than the orginial. The delusional person may believe that the clone is an “evil twin” or just a doppelgänger with different ideas and behaviors. For example, a teenager believed that her next-door neighbor had remade herself (like Jennifer Jason Leigh’s character in Single White Female) into an identical twin. In another case, following surgery, a man came to believe that his brain had been transplanted into another person and that this other person was now his double.

4. Ekbom Syndrome

A woman, age 77, complained to doctors of an infestation of bugs underneath her skin and crawling around inside her. She also imagined bugs on the surface of her skin. There were, of course, no bugs. Ekbom syndrome, or delusional parasitosis, is the belief that one is infested with bugs, worms, or other parasites when they are not. People with this delusion usually seek medical attention rather than psychological treatment, since they consider their imaginary infestation to be real and in need of a cure. (Morgellons “disease” is a specific subtype of Ekbom syndrome, which causes people to believe that they are contaminated with fibers, dirt, or other substances.)

The movie Bug, which stars Ashley Judd, featured a character who believed he had been infested with bugs by evil government scientists. He enticed Judd’s character into a relationship, and she began to believe his increasingly bizarre conspiracy theories. Which brings us to the next syndrome…

5. Folie a Deux

A delusion that originates with one person is transmitted to another person as if the delusion were contagious. The second person becomes “infected” with the delusion and believes it just as strongly as the person who originated it. Folie a deux requires an intimate or insular living arrangement so that constant exposure to the delusion causes it to spread.

When more than two people fall under the spell of a delusion, it’s known as folie a beaucoup. For example, in 1962, a group of women working in a factory came to believe that they had been bitten by a bug. One woman (the “carrier” of the delusion) began displaying symptoms of illness and attributed it to a bug bite. One by one, the others began manifesting symptoms and attributing them to a bug bite. No infected bug was ever found, and doctors discovered no identifiable cause for their symptoms. The entire episode was attributed to mass hysteria and became known as The Great June Bug Epidemic.


These syndromes often co-occur with schizophrenia or other profound mental disorders, or as the result of a brain injury or lesion. The man who fingerprinted his daughter believed that thoughts had been implanted in his head through involuntary hypnosis. He also believed that he was being spied on and that his phones were tapped. Delusions can also exist alongside each other. For example, a person with Capgras syndrome may also suffer from the Fregoli delusion and/or the syndrome of subjective doubles (or any number of other delusions).



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