The Social and Treatment Consequences of a Shared Delusional Disorder in a Homeless Family

| April 29, 2011 | 0 Comments

by Richard C. Christensen, MD, MA, and Erwin Ramos, MD
Dr. Christensen is Professor and Chief, Division of Public Psychiatry, University of Florida College of Medicine, Gainesville, Florida; and Dr. Ramos is Fellow in Public Psychiatry, Department of Psychiatry, University of Florida College of Medicine, Gainesville, Florida.

Innov Clin Neurosci. 2011;8(4):42–44

Funding: No funding was received for the development of this article.

Financial disclosures: The authors have no conflicts of interest relevant to the content of this article.

Key words: Delusional disorder, shared delusional disorder, folie a’ deux, folie a’ famille, homelessness, extreme poverty

Abstract: Objective: Delusional disorder is defined as a fixed, false belief that is held by a person despite evidence to the contrary. Shared psychotic disorder, also known as folie a’ deux, psychosis by association and induced psychotic disorder, is an uncommon and unique psychiatric disorder. It is even more unusual when it occurs within families (folie a’ famille). Case Presentation: This case report describes the occurrence of a shared delusion within a family consisting of an adult son and two elderly parents. The shared delusion, which was the belief that a large financial settlement was awaiting to be disbursed to the family members by the local law enforcement agency, contributed to their state of homelessness and rejection of all offers of assistance from service providers. Conclusion: The impact of this shared psychotic disorder contributed to the family’s state of extreme poverty and homelessness, which, as a consequence, greatly impeded the initiation of evidence-based therapeutic interventions.


Shared psychotic disorder is an uncommon variant of delusional disorder.[1] According to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR), shared psychotic disorder is characterized by the development of a delusion in the context of a close relationship with another person(s), who has an already established delusion.[2] In 1887, Lasegue and Falret[3] first utilized the term folie a’ deux or insanity by association in their classic paper entitled, “Lafolie a deux.” However, only a small percentage of cases involve more than two persons (folie a’ troix), especially a family (folie a’ famille).[4,5] To the best of our knowledge, we describe the first case of a shared delusional disorder occurring within a homeless family comprising an adult son and two elderly parents.

Case Report

JB was a 26-year-old Caucasian man who lived in a car on the urban streets with his two aging parents. His mother, Mrs. B, was 63 years old and his father, Mr. B, was 84 years old. Each of these individuals denied previous treatment for psychiatric illness.

None had serious medical conditions with the exception of Mr. B, who suffered from mild emphysema. The family had taken to life on the streets after a brief stay at our urban shelter for homeless persons. They had arrived at the shelter in the immediate days following their eviction from a leased home in the community after they were unable to pay their monthly rent. However, their stay at the shelter ended abruptly when a case management team met with the parents to discuss their social security benefits and housing options. When asked the reasons behind the familial decision to abruptly leave, JB explained that they were planning to move to Texas upon receipt of a large financial settlement they had won from the city for the unlawful eviction from their home. He intended to retrieve the funds the next day from the county jail where they were being held in the “claims office.” Once they had their money in hand, he said they would be leaving for Texas where he had a deployment date set with the Merchant Marines. From his view, they no longer needed the shelter’s services since the financial largesse would be “more than enough…I’m talking a million dollars or more.” When both of the parents were questioned, together and separately, they recounted in detail precisely the same story.

The family proceeded to take up lodging in their car that was parked near the shelter. They would visit the shelter each day for meals, showers, and change of clothing, but declined housing. The street outreach team affiliated with the facility visited the family each day and, at least once per week, the shelter’s psychiatrist (author Christensen) would attempt to foster relationships, assess the medical status of the parents, and persuade the family to accept services. However, on each encounter, the given rationale for declining services would always be the same: “JB is at the county jail at the claims office. We should have our money later today…tomorrow at the latest. Then we’ll be going to Texas.” When JB was questioned, he was just as adamant that it would be “either today or tomorrow” before personnel at the jail would release the large financial settlement. When asked what the persons at the jail were telling him each day he came with his request, he reported, “Oh, they’re always making up some cover story or another to protect the Sheriff, but I have lawyers working on this and we should have all the money by tomorrow.” It should be noted that a public records search turned up no evidence there had ever been legal proceedings involving the family and the city.

After two months of living on the streets, the parents stated they were “advised” by JB to not discuss the details of the settlement and financial largesse any further with the psychiatrist. On several occasions, Mrs. B would become very irate with her husband when he was engaged by the visiting psychiatrist. JB also declined to talk specifics because he said his lawyers “told him not to.” However, they felt less constrained talking to the outreach workers and would consistently repeat the belief that their lawsuit funds would be released any day.

The family continued to live on the streets for nearly nine months until it was discovered by our center’s case management staff that Mr. B had accumulated nearly five thousand dollars of monthly social security benefits that had been automatically deposited into his banking account. Within two days, the family stated they were headed for Texas and JB noted that his lawyers assured him they would continue to work on the case and secure his financial settlement. He stated, “There’s no reason we have to stay here since they’ll send me the money…I’m due to ship out with the Merchant Marines next week.” The family subsequently left the city and was lost to follow up.


This case report underscores much of what we understand today about shared psychotic disorder. However, the family’s state of homelessness and chronic poverty creates a unique lens from which to view this uncommon clinical syndrome. Most significantly, the transfer of what we would describe as a mixed delusion of grandeur and paranoia occurred within a family (folie a’ famille) rather than being limited to just two persons (folie a’ deux). What has been derived from other case reports describing this rare disorder is the finding that the persons who share the delusion have been closely associated for an extended period of time and tend to live in relative social isolation.6 In fact, what we could gather through multiple sources over time (e.g., workers from an adult protective services agency) describes a family that, even prior to being evicted from their house, lived without friends or in communication with relatives. Moreover, they seemingly had no connections to social, community, or religious groups. None of the family members had been employed for many years, including JB. Hence, even prior to becoming homeless, for all intents and purposes, this was a nuclear family that was socially isolated and insular. However, their subsequent state of homelessness and extreme poverty magnified this pronounced social and psychological marginalization and, in our view, contributed powerfully to the cohesive familial bond created by the shared psychosis. Others have suggested that the shared delusion serves as a unifying force for the family and protection from what is perceived as a threatening and hostile environment.[7]

The corpus of literature describing this disorder contends that the person who first has the delusion (oftentimes referred to as the “dominant person” or the “primary case”) is often suffering from a chronic mental illness and is typically the most influential person in the diad or triad. The person, or persons, who accept the delusional system are frequently more passive, less intelligent, and lacking the force of character and self esteem evinced by the inducer of the delusion.[8] Seemingly this was the situation with this family in that JB, the son, was clearly the dominant, most influential person in the web of relationships. Both parents had become, over the years and especially during this time of homelessness, pathologically dependent upon him for direction and care. His perspective and worldview were unquestionably and passively accepted by both parents throughout this period of intense personal and social instability. Although it cannot be proven with certainty, JB’s personal history would suggest the presence of a longitudinal psychiatric disturbance since it appears he had never been employed for any significant period of time, had not experienced an intimate relationship outside his family, nor had he ever lived apart from his parents. His growing paranoia throughout this period was evidenced by his concerted effort to prevent his parents from discussing any of the family affairs with the psychiatrist affiliated with the shelter. This is consistent with the theory that the sharing of the delusion within the family creates a type of “pseudocommunity” that prevents intrusion from the outside world and contributes, in the extreme, to a web of pathological relationships.[9]


The state of extreme poverty and homelessness within which this family was mired profoundly interfered with attempts to initiate and deliver meaningful therapeutic interventions. Most authors consider the central therapeutic modality targeting a shared delusional disorder to be the separation of the inducer of the delusion (JB) from those who have been induced (Mrs. and Mr. B).[10] However, it became abundantly clear that the parents would not willingly separate from their son while living unsheltered on the streets. Moreover, the son’s delusional system evidenced a steadfast conviction and pervasiveness that extinguished all insight into the nature of his psychotic disorder. Unfortunately, this shared delusional disorder has led to devastating psychosocial ramifications for this particular family and, given the history of service and treatment rejection, very likely continues to do so today.

1.    Manschreck TC. Delusinal disorder and shared psychotic disorder. In: Sadock BJ, Sadock (eds). Comprehensive Textbook of Psychiatry, Seventh Edition. Philadelphia: Lippincott Williams and Wilkins; 2000: 1245–1247.
2.    American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. Fourth Edition, Text Revision. Washington DC: American Psychiatric Press Inc.; 2000.
3.    Lasegue C, Falret J. La folie a deux. Ann Med Psychol. 1877;18:321.
4.    Wehmeir PM, Barth N, Remschmidt H. Induced delusional disorder. A review of the concept and an unusual case of folie a’ famille. Psychopathology. 2003;36(1):37–45.
5.    Goh YL, Wong HK. Folie a famille: a case report of three sisters. Hong Kong Journal of Psychiatry. 2007;17:64–66.
6.    Arnone D, Patel A, Tan GM. The nosological significance of folie a deux: a review of literature. Ann Gen Psychiatry. 2006;5:11.
7.    Thaddeus U, Russel C. The delusional parent: family and multisystemic issues. Can J Psychiatry. 1997;42:617–622.
8.    Manschreck TC: Delusinal disorder and shared psychotic disorder. In: Sadock BJ, Sadock (eds). Comprehensive Textbook of Psychiatry, Seventh Edition. Philadelphia: Lippincott Williams and Wilkins; 2000: 1257.
9.    Srivastava A., Borkar HA. Folie a’ famille. Indian J Psychiatry. 2010. 52(1):69–70.
10.    Mouchet-Mages S, Gourevitch R, Loo H. Folie a deux: update of an old concept regarding two cases. Encephale. 2007;34 (1):31–37.

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Category: Case Report, Mental Disorders, Past Articles, Psychiatry, Psychology, Schizophrenia

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