“A disorder in which a person holds a delusional belief that different people are in fact the same person” – Wiki

What if your sister, your boyfriend, your boss and your next-door neighbor were really all the same person, who was constantly altering their appearance in order to fool you?  Sufferers of Fregoli delusion believe (very, very mistakenly) that different people in their lives are actually the very same person, using an elaborate array of disguises and costumes to trick them.  Often this belief is of a paranoid nature with the delusional person believing that they are being persecuted by the person whom they believe to be following them.  The condition is named after the Italian actor Leopold Fregoli who was renowned for his ability to make quick changes of appearance during his stage act.  It was first reported 1927 by two psychiatrists who discussed the case study of a 27 year old woman who believed that she was being persecuted by two actors whom she often went to see at the theatre. She believed that these people “pursued her closely, taking the form of people she knows or meets.”

It is related to Capgras Delusion (another rare delusional misidentification syndrome psychiatric disorder) that causes a person to believe their friends or family members have been replaced with impostors.  And, like Capgras, psychiatrists believe it is the result of troubles with facial perception, which can be caused by traumatic brain injury.

The story of Mrs. T.

Mrs. T, a 69-year old married housewife recently discharged from a local hospital after her first psychiatric admission, went to another doctor for a second opinion.  At the time of her admission earlier in the year she had received the diagnosis of atypical psychosis because of her belief that her husband had been replaced by another unrelated man.  She refused to sleep with the impostor, locked her bedroom and door at night, asked her son for a gun, and finally fought with the police when attempts were made to hospitalize her.  At times she believed her husband was her long deceased father.  She easily recognized other family members and would only misidentify her husband.

Betty’s story

Betty believed that a former lover and his girlfriend were monitoring her. She was convinced that they were occupying neighboring homes and garages, rapidly changing their identities, all in an attempt to prevent her from telling family and friends about her previous affair with the gentleman. Betty thought that these people were stunning masters of disguise, that they could change their facial appearance, clothes, and even their sex at a moment’s notice.

The paranoia induced by this condition has made it a common tool in science fiction books and films, such as Invasion of the Body Snatchers, Total Recall and The Stepford Wives.

Treatment and prognosis for delusional misidentification syndromes as a result of neurological damage vary widely.  In some case studies, the patients recovered slowly over time.  In other cases, especially in those of elderly patients, the delusions may continue or become worse, progressing into general dementia.  Patients have responded with varying success to an array of treatments including cognitive and behavioral therapies (CBT), and the use of medications such as anti-psychotics, anti-convulsants, sedatives, and tranquilizers