The Fregoli syndrome, also called as delusion of doubles, is a rare mental condition where an affected person strongly believes that the different people that he encounters are actually just a single individual in disguise. Most of the time, the patient also has this delusion that this impostor in disguise is out to kill him or her.

The misidentification in Fregoli delusion is not only limited to people. In a few cases, people with Fregoli delusion can also see different animals, objects, or even places, as the impostor in disguise. This particular syndrome is related to the paranoid psychiatric disorder and is often classified as both a delusional misidentification syndrome and a monothematic delusion. Monothematic delusions are those cases where there’s only one delusional topic involved.

Aside from the delusion, the syndrome is also characterized by deficits in visual memory, deficit in self-awareness, inability to monitor oneself, lack of cognitive flexibility, seizures, and other epileptogenic activities.

facelessCredit: Hubert Figuière

History of the Fregoli Delusion

The syndrome was first reported in 1927 in a paper written by P. Courbon and G. Fail. In the report was a discussion about a woman, 27 years of age, who had this strong belief that two actresses whom she often went to see at theatre performances were persecuting her. According to the woman, these two actresses were disguising themselves as people she knew.

The syndrome is named after an Italian actor named Leopold Fregoli. Leopold Fregoli was famous for his ability to change his wardrobe appearances on stage very quickly. 

Cause of the Fregoli Delusion 

The causes of Fregoli syndrome is usually attributed to the following:

Traumatic brain injury or lesions on the brain

An organic brain lesion, especially on the right temporal lobe or the fusiform gyrus, can cause changes in the associative nodes of the brain. The associative nodes are important for face recognition. Damage to these nodes due to a brain injury can cause misinterpretation of people’s faces.

Also, a damage incurred to the right forward or to the left temporal region of the brain can cause deficits in a person’s self-awareness and self-monitoring capabilities.

An accident or degeneration due to aging can cause brain lesions.

Long term treatment with levodopa (L-Dopa) 

Levodopa is a drug used to treat the symptoms of Parkinson’s disease. A person who undergoes long use of the drug and at some point start taking decreased level of the drug, delusions can develop.

Treatment of Fregoli Delusion

Treatment of the syndrome mainly involves pharmacotherapy through antipsychotic, antidepressant, and anticonvulsant drugs.

Tricyclic antidepressants (TCA) were once primarily used for treating the symptoms of Fregoli but the modern antidepressants cause fewer side effects and are now used more often than TCAs. These antidepressants include venlafaxine and fluoxetine.

Trifluoperazine is a typical antipsychotic used for treatment of Fregoli. This drug is usually given if other signs of psychological orders are present with the syndrome.

The treatment for Fregoli may not be very successful but they have proven to be effective in preventing more symptoms to occur.