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Folie à deux

For other uses, see Folie à deux (disambiguation).
Induced delusional disorder
Classification and external resources
ICD-10 F24
ICD-9 297.3
DiseasesDB 34350
eMedicine med/3352
NCI Folie à deux
Patient UK Folie à deux
MeSH D012753

Folie à deux (/fɒˈli ə ˈd/; Template:IPA-fr; French for "a madness shared by two"), or shared psychosis, is a psychiatric syndrome in which symptoms of a delusional belief are transmitted from one individual to another.[1] The same syndrome shared by more than two people may be called folie à trois, folie à quatre, folie en famille or even folie à plusieurs ("madness of many"). Recent psychiatric classifications refer to the syndrome as shared psychotic disorder (DSM-IV) (297.3) and induced delusional disorder (F.24) in the ICD-10, although the research literature largely uses the original name. The disorder was first conceptualized in 19th-century French psychiatry by Charles Lasègue and Jean-Pierre Falret and so also known as Lasègue-Falret Syndrome.[2][3]


This syndrome is most commonly diagnosed when the two or more individuals concerned live in proximity and may be socially or physically isolated and have little interaction with other people.

Various sub-classifications of folie à deux have been proposed to describe how the delusional belief comes to be held by more than one person.

  • Folie imposée is where a dominant person (known as the 'primary', 'inducer' or 'principal') initially forms a delusional belief during a psychotic episode and imposes it on another person or persons (known as the 'secondary', 'acceptor' or 'associate') with the assumption that the secondary person might not have become deluded if left to his or her own devices. If the parties are admitted to hospital separately, then the delusions in the person with the induced beliefs usually resolve without the need of medication.
  • Folie simultanée describes either the situation where two people considered to suffer independently from psychosis influence the content of each other's delusions so they become identical or strikingly similar, or one in which two people "morbidly predisposed" to delusional psychosis mutually trigger symptoms in each other.[4]

Folie à deux and its more populous cousins are in many ways a psychiatric curiosity. The current Diagnostic and Statistical Manual of Mental Disorders states that a person cannot be diagnosed as being delusional if the belief in question is one "ordinarily accepted by other members of the person's culture or subculture" (see entry for delusion). It is not clear at what point a belief considered to be delusional escapes from the folie à... diagnostic category and becomes legitimate because of the number of people holding it. When a large number of people may come to believe obviously false and potentially distressing things based purely on hearsay, these beliefs are not considered to be clinical delusions by the psychiatric profession and are labelled instead as mass hysteria.

Related phenomena

Reports have stated that a similar phenomenon to folie à deux had been induced by the military incapacitating agent BZ in the late 60s,[5][6]

Individual cases

In the case of twin sisters Ursula and Sabina Eriksson,[7] Ursula ran into the path of an oncoming articulated lorry, sustaining severe injuries. Sabina then immediately duplicated her twin's actions by stepping into the path of an oncoming car; she survived the impact. It was later claimed that Sabina Eriksson was a 'secondary' sufferer of folie à deux, influenced by the presence or perceived presence of her twin sister, Ursula – the 'primary'. Sabina later told an officer at the police station, "We say in Sweden that an accident rarely comes alone. Usually at least one more follows – maybe two."[8] However, upon her release from hospital, Sabina behaved erratically before stabbing a man to death.[9][10][11]

Another case involved Margaret and her husband Michael, both aged 34 years, who were discovered to be suffering from folie à deux when they were both found to be sharing similar persecutory delusions. They believed that certain persons were entering their house, spreading dust and fluff and "wearing down their shoes". Both had, in addition, other symptoms supporting a diagnosis of emotional contagion, which could be made independently in either case.[12]

Film and literature

William Friedkin's 2006 film Bug is about a woman who enters into a relationship with a man and begins to share his delusion that the government has infected them with microscopic bugs.

In Juan Carlos Fresnadillo's 2011 film Intruders, Clive Owen's character is diagnosed with Folie à deux, because he has an extraordinarily close relationship with his daughter, and he and his daughter are the only two who see and interact with the titular intruder, "Hollowface."

The 2011 independent film, Apart depicts two lovers affected and diagnosed with induced delusional disorder, trying to uncover a mysterious and tragic past they share. In a 2011 interview, director Aaron Rottinghaus stated the film is based on research from actual case studies.[13]

In the X-Files episode entitled "Folie à Deux" shared psychosis is brought up by Scully as a possible explanation for the sudden conviction of Mulder, that an apparently mentally ill man had correctly identified his superior as a monster hiding in human shape.

The Simpsons episode "Lisa the Drama Queen" introduces a character called Juliet Hobbes, who retreats into a fantasy world of her own creation. After an amount of time spent in her company, Lisa and eventually Kearney experience Folie imposée which alters their perceptions of reality. The episode was loosely based around the Peter Jackson film Heavenly Creatures, which in turn was based on the Parker-Hulme murder case in which two schoolgirls, one named Juliet, were suspected to be suffering from folie à deux.

The Suite Life of Zack & Cody episode "The Suite Smell of Excess" involved the central characters returning from a parallel world. Their mother claimed that their experience was a result of them having the same dream, referring to it as folie à deux.

Fall Out Boy released an album called Folie à Deux.

Perfect Blue, a 1997 Japanese animated psychological thriller film directed by Satoshi Kon involves folie à deux as a major theme and plot line.

In an episode of CSI Miami, a husband and wife kidnap and murder girls. It is described as folie à deux where the wife is the superior person influencing the husband to kill them.

Recording artist Meshell Ndegeocello's 2014 album Comet, Come to Me includes a song entitled "Folie à Deux," about a dysfunctional romantic relationship.

In his account of the 1961 Betty and Barney Hill's UFO abduction entitled "The Interrupted Journey"; author John G. Fuller records psychiatrist Dr. Duncan Stephens' attempt at explaining the simultaneous amnesia suffered by the Hill's as a possible case of folie à deux.

In an episode of Kwaenchana, sarangiya, a couple was diagnosed with shared psychotic disorder. They both had visual hallucinations of cockroaches in their bedroom.

See also


  1. "Dr. Nigel Eastman in the BBC documentary 'Madness In The Fast Lane'". 2010-09-24. Retrieved 2011-05-31. 
  2. Berrios G E (1998) Folie à deux (by W W Ireland). Classic Text Nº 35. History of Psychiatry 9: 383–395
  3. Arnone, Danilo; Anish Patel; Giles Ming-Yee Tan (2006-08-08). "The nosological significance of Folie à Deux: a review of the literature". Annals of General Psychiatry 5: 11. ISSN 1744-859X. PMC 1559622. PMID 16895601. doi:10.1186/1744-859X-5-11. 
  4. Dewhurst, Kenneth; Todd, John (1956). "The psychosis of association: Folie à deux.". Journal of Nervous and Mental Disease 124: 451–459. doi:10.1097/00005053-195611000-00003. 
  5. "Incapacitating Agents". Retrieved 2011-05-31. 
  6. "Medscape Access". Retrieved 2011-05-31. 
  7. "TV Review: Madness In The Fast Lane – BBC1". The Sentinel. 11 August 2010. Retrieved 31 August 2010. 
  8. "TV Preview: Madness In The Fast Lane – BBC1, 10.35 pm". The Sentinel. 10 August 2010. Retrieved 31 August 2010. 
  9. "Why was Sabina Eriksson free to kill?". The Sentinel. 3 September 2009. Retrieved 31 August 2010. 
  10. "Could M6 film of killer have saved victim?". The Sentinel. 7 September 2009. Retrieved 31 August 2010.  |first1= missing |last1= in Authors list (help)
  11. Madness In The Fast Lane Retrieved 3 February 2011.
  12. This case study is taken from Enoch and Ball's 'Uncommon Psychiatric Syndromes' (2001, p181)
  13. Cangialosi, Jason. "SXSW 2011: Interview with Aaron Rottinghaus, Director of 'Apart'". Yahoo!. Retrieved 13 August 2013. 

Further reading

  • Halgin, R. & Whitbourne, S. (2002) Abnormal Psychology: Clinical Perspectives on Psychological Disorders. McGraw-Hill. ISBN 0072817216
  • Enoch, D. & Ball, H. (2001) Folie à deux (et Folie à plusieurs). In Enoch, D. & Ball, H. Uncommon psychiatric syndromes (Fourth edition). London: Arnold. ISBN 0340763884
  • Wehmeier PM, Barth N, Remschmidt H (2003). "Induced delusional disorder. a review of the concept and an unusual case of folie à famille". Psychopathology 36 (1): 37–45. PMID 12679591. doi:10.1159/000069657. 
  • Hatfield, Elaine, Caccioppo, John T., & Rapson, Richard L. (1994). Emotional contagion (Studies in Emotional and Social Interaction). Cambridge, UK: Cambridge University Press. ISBN 0-521-44948-0. 
  • Metzner, Ralph, editor. Ayahuasca: Human Consciousness and the Spirits of Nature. New York, NY: Thunder's Mouth Press. ISBN 1-56025-160-3.