Any Porth in a Storm: The Long-Distance Walk that Goes South (2021), a travelogue by Oscar Burton, has a chapter with the title Folie à deux, referencing meeting another person dressed identically and with the same equipment who was also walking the 1000 km South West Coast Path in England. It is suggestive of the mental decay of the protagonist which becomes evident later in the story. The upcoming DC Comics film Joker: Folie à Deux, a sequel to Joker (2019), shares its subtitle with the disorder. Six Feet Under Season 4, Episode 3 (2004), George mentions Folie à deux to Ruth. See also
References
Further reading
Books
Enoch, D., and H. Ball. 2001. "Folie à deux (et Folie à plusieurs)." In Uncommon psychiatric syndromes (4th ed.). London: Arnold. ISBN 0340763884
Halgin, R., and S. Whitbourne. 2002. Abnormal Psychology: Clinical Perspectives on Psychological Disorders. McGraw-Hill. ISBN 0072817216
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. Ketchum, James S. 2007. Chemical Warfare: Secrets Almost Forgotten A Personal Story of Medical Testing of Army Volunteers (2nd ed.). Chembook, Inc. ISBN 1424300800; ISBN 978-1424300808. Metzner, Ralph, ed. (1999-06-02). Ayahuasca: Human Consciousness and the Spirits of Nature. New York, NY: Thunders Mouth Press. ISBN 1-56025-160-3. Journal articles
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. doi:10.1159/000069657. PMID 12679591. S2CID 144398794. Abu-Salha, Mohammad (1998). "Folie á Deux: Two Case Reports".
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
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 (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
Either the situation where two people considered to independently experience psychosis influence the content of each others 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.Folie à deux and its more populous derivatives are psychiatric curiosities. 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 persons culture or subculture." 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.