Delusions of false identification are a type of delirium that is especially striking because it involves the misrecognition of other people, sometimes even oneself.

In this article we will discuss the symptoms and causes of Frégoli syndrome , one of the most popular false identification delusions.

What is Frégoli’s syndrome?

Frégoli’s syndrome is a delusion consisting of the belief that one or more known persons are being supplanted by someone wearing a disguise or otherwise changing their appearance.

It is often associated with a paranoid component, as people with Frégoli’s syndrome often think that the impersonator is after them to harm them or at least to harm them.

This is a monothematic delirium classified within the category of what we know as “delusions of false identification”. It is related to disorders such as psychosis, dementia and brain injuries.

Like other similar delusions, Frégoli’s syndrome is associated with a deficit in face recognition : the perception of unknown faces would trigger the misidentification of these with other more familiar ones, usually loved ones or celebrities. It can also be influenced by other senses, such as hearing and smell.

History of the disorder

Frégoli’s syndrome was described by two French psychiatrists, Courbon and Fail , in their 1927 article Syndrome d’illusion de Frégoli et schizophrénie (“Frégoli’s illusion syndrome and schizophrenia”).

Courbon and Fail explained the case of a 27-year-old domestic servant, who was very fond of theatre, and who believed that the famous actresses Robine and Sarah Bernhardt were disguising themselves as people she knew in order to influence her thoughts and behaviour negatively – for example by preventing her from working or forcing her to masturbate.

The name “Frégoli’s syndrome” refers to the Italian actor Leopoldo Frégoli , who was known for his ability to transform, imitate and disguise.

Oliver Sacks popularized this delusion through his 1985 book The Man Who Mistaken His Wife for a Hat. Since then he has inspired several films, such as Total Challenge, Perfect Women and Anomaly.

Since its description in 1927, only 40 cases have been documented worldwide, although it is believed that this disorder is likely to be under-diagnosed.

Signs and symptoms

People with Frégoli’s syndrome usually present a series of alterations that predispose them to the appearance of symptoms; in particular, deficits have been detected in visual memory, self-monitoring, executive functions, cognitive flexibility and self-awareness.

This means that they may have more difficulty remembering visual information, controlling and monitoring their own behavior, differentiating themselves from others, or thinking about several concepts at once.

Frégoli’s syndrome is also more likely in people with a history of seizures , especially if they have occurred during seizures.

The core symptoms of this disorder often coexist with hallucinations and other delusions. Delusions are beliefs that are held in an immovable form despite evidence that conclusively disproves them, whereas hallucinations consist of the perception of external stimuli that do not exist.

Causes of Frégoli syndrome

Psychosis is one of the most frequent causes of Frégoli’s syndrome. Delusions are one of the cardinal symptoms of schizophrenia and other similar disorders . In this case we speak in most cases of a persecutory delirium.

In diseases that affect the brain, particularly dementias, psychotic delusions such as Frégoli’s are common as the brain involvement progresses.

Another common cause is treatment with levodopa , a catecholaminergic drug that is primarily used to treat Parkinson’s disease. The longer the treatment and the higher the dose, the more likely it is that hallucinations and especially delusions will develop.

Traumatic brain injury can lead to the appearance of Frégoli syndrome; in particular, cases have been documented in persons with frontal lobe injuries, in the temporoparietal region and in the fusiform gyrus , which is involved in visual recognition and contains a specific area for the faces, the ventral fusiform cortex.

The alterations in selective attention, working memory or cognitive flexibility that characterize many Frégoli patients are common consequences of brain injuries and predispose to the appearance of this and other delusions.

Other false identification delusions

Delusions of false identification consist of misrecognition of people, places or other stimuli. Among these we find several disorders very similar to Frégoli’s syndrome.

The best known of these delusions is the Capgras syndrome or Sosias delirium , in which a loved one is believed to have been replaced by an identical double. As with Frégoli’s syndrome, this is most often a persecutory delusion in which negative intentions are attributed to the alleged impostor.

In the delirium of intermetamorphosis , also described by Courbon, the patient believes that the people around him exchange identity, while maintaining the same appearance.

The syndrome of the subjective doubles consists of the belief that one or more doubles with their own personality and body usurp the identity.

Treatment of these syndromes

Cognitive-behavioral treatments for delusions focus on cognitive restructuring through symptom normalization, non-confrontational verbal challenge, and reality tests to refute client hypotheses.

In cases of psychosis, whether or not induced by brain disease, symptoms may subside with the use of antipsychotic drugs, which primarily modify dopaminergic activity.

Anticonvulsant drugs are effective in combating epilepsy, including the delusional symptoms that can occur in the context of this disease.