Shared psychotic disorder

Shared Psychotic Disorder 1037
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Shared psychotic disorder, a rare and atypical psychotic disorder, occurs when an otherwise healthy person (secondary partner) begins believing the delusions of someone with whom they have a close relationship (primary partner) who is already suffering from a psychotic disorder with prominent delusions. This disorder is also referred to as "folie á deux."


In cases of shared psychotic disorder, the primary partner is most often in a position of strong influence over the other person. This allows them, over time, to erode the defenses of the secondary partner, forcing their strange belief upon them. In the beginning, the secondary partner is probably healthy, but has such a passive or dependent relationship with the primary partner that imposition of the delusional system is but a matter of time. Most of the time, this disorder occurs in a nuclear family. In fact, more than 95% of the cases reported involved people in the same family. Without regard to the number of persons within the family, shared delusions generally involve two people. There is the primary, most often the dominant person, and the secondary or submissive person. This becomes fertile ground for the primary (dominant) partner to press for understanding and belief by others in the family.

Shared psychotic disorder has also been referred to by other names such as psychosis of association, contagious insanity, infectious insanity, double insanity, and communicated insanity. There have been cases involving multiple persons, the most significant being a case involving an entire family of 12 people (folie á douze).

Causes and symptoms


Given the fact that the preponderance of cases occur within the same family, the theory about the origins of the disorder come from a psychosocial perspective. Approximately 55% of secondary cases of the disorder have first-degree relatives with psychiatric disorders, not including the primary partner. This is not true of individuals with the primary diagnosis , as they showed a roughly 35% incidence.

There are several variables which have great influence on the creation of shared psychotic disorder. For example, family isolation, closeness of the relationship to the person with the primary diagnosis, the length of time the relationship has existed, and the existence of a dominant-submissive factor within the relationship. The submissive partner in the relationship may be predisposed to have a mental disorder. Often the submissive partner meets the criteria for dependent personality disorder . Nearly 75% of the delusions are of the persecutory type.

An example of shared psychotic disorder involving the delusion of persecution, is that of a 52-year-old married female and her 48-year-old husband with multiple sclerosis, who believed that they were being harassed and watched by the Irish Republican Army (IRA). They were hospitalized and both became stable after two weeks on an antipsychotic medication. However, an interesting point in this case is that they were separated for that two-week period. The general consensus has been that, once separated, the submissive partner will let go of the delusion, that it would resolve itself simply due to separation. That did not happen in this case. Both partners had to be treated with proper medications before the delusion resolved.

In a case involving a middle-aged mother and an adolescent daughter, the delusions were multifaceted. The mother held the persecutory belief that someone in her neighborhood was manufacturing illegal drugs of some sort, and that they were periodically spraying something odorless, tasteless, and invisible into the air. The sprayed substance made her and her teen-aged daughter "act crazy." Oddly enough, the effects of the spraying began shortly after the husband left for work in the morning, and resolved shortly before he returned in the afternoon. The family raised ducks at their home, and the mother and daughter believed that the men making the illegal drugs were using the family ducks "as a food source" in order to stay near their hideout and avoid detection by police. Finally, mother and daughter also believed that occasional gunshots in their countryside landscape were meant as warnings to prevent anyone from learning about the misdeeds of the drug makers. This case was revealed when the daughter ran away from home, fearing that men with guns were coming to kill them. She was subsequently placed in the care of a child protective services agency, and the bizarre stories began to unfold. Both mother and daughter received psychiatric care.


The principal feature of shared psychotic disorder is the unwavering belief by the secondary partner in the dominant partner's delusion. The delusions experienced by both primary partners in shared psychotic disorder are far less bizarre than those found in schizophrenic patients; they are, therefore, believable. Since these delusions are often within the realm of possibility, it is easier for the dominant partner to impose his/her idea upon the submissive, secondary partner.


Little data is available to determine the prevalence of shared psychotic disorder. While it has been argued that some cases go undiagnosed, it is nevertheless a rare finding in clinical settings.


A clinical interview is required to diagnose shared psychotic disorder. There are basically three symptoms required for the determination of the existence of this disorder:

  • • An otherwise healthy person, in a close relationship with someone who already has an established delusion, develops a delusion himself/herself.
  • • The content of the shared delusion follows exactly or closely resembles that of the established delusion.
  • • Some other psychotic disorder, such as schizophrenia , is not in place and cannot better account for the delusion manifested by the secondary partner.


The treatment approach most recommended is to separate the secondary partner from the source of the delusion. If symptoms have not dissipated within one to two weeks, antipsychotic medications may be in order.

Once stabilized, psychotherapy should be undertaken with the secondary partner, with an eye toward integrating the dominant partner, once he/she has also received medical treatment and is stable.


If the secondary partner is removed from the source of the delusion and proper medical and psychotherapeutic treatment are rendered, the prognosis is good. However, as stated above, the separation alone may not be successful. The secondary partner may require antipsychotic medication. Even after treatment, since this shared psychotic disorder is primarily found in families, the family members tend to reunite following treatment and release. If family dynamics return to pretreatment modes, a relapse could occur. Periodic monitoring by a social services agency is advised for as long as a year following treatment.


In an effort to prevent relapse, family therapy should also be considered to re-establish the nuclear family and to provide social support to modify old family dynamics. The family cannot continue in isolation as it did in the past, and will require support from community agencies.



American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th edition, text revised. Washington, DC: American Psychiatric Association,2000.

Kaplan, Harold and Benjamin Sadock. Synopsis of Psychiatry 8th edition. New York: Lippincott, Williams and Wilkins,1997.


Lai, Tony T. S, W. C. Chan, David M. C. Lai, S. W. Li. "Folie á deux in the aged: A case report." Clinical Gerontologist 22 (2001): 113-117.

Malik, Mansoor A. and Serena Condon. "Induced psychosis (folie á deux) associated with multiple sclerosis." Irish Journal of Psychological Medicine 17 (2000): 73-77.

Jack H. Booth, Psy.D.

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George Tafuna
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Feb 3, 2010 @ 1:01 am
The article is very educative more expecially in Zambia where family Psychiatry is not practiced. How ever we would like to have articles giving a crue on tips on how to conduct the following
- Social Study
- Home Visits
- Establishment of half way homes
Thank you

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