Shared Delusional Disorder and its treatments

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Shared Delusional Disorder and its treatments

Post04 Feb 2016

Shared Delusional Disorder

A delusional disorder shared by two or more people with close emotional links. The dominant person in this relationship has delusional disorder and convinces the nondominant person to adopt these delusional beliefs. Usually the nondominant person regains sanity once separated from the psychotic dominant person.


Chronic for psychotic teacher of the delusion, but short-lived for the pupil if separated from the teacher.

Only one of the people suffers from a genuine psychotic disorder; the delusions are induced in the other(s) and usually disappear when the people are separated. Unlike schizophrenia, it has; no prominent hallucinations, no disorganized speech, no grossly disorganized or catatonic behavior, no negative symptoms (i.e., diminished emotional expression or avolition), psychosocial functioning is not markedly impaired, and behavior is not obviously odd or bizarre.

Occurs where delusions are not widely accepted beliefs in the individual's culture. Delusions last longer than any associated depression or mania.

From: Treatments for delusional disorder, from Authors: Skelton M, Khokhar W, Thacker SP.
Delusional disorder is a mental illness in which long-standing delusions (strange beliefs) are the only or dominant symptom. There are several types of delusions. Some can make the person affected feel that they are being persecuted or can cause anxiety that they have an illness or disease that they do not have. People can have delusions of grandeur, so that they feel like they occupy a high position or are famous. Delusions can also involve jealousy of others or involve strange beliefs about body image, such as that they have a particular bodily defect.

Delusional disorder is considered difficult to treat. Antipsychotic drugs, antidepressants and mood-stabilising medications are frequently used to treat this mental illness and there is growing interest in psychological therapies such as psychotherapy and cognitive behavioural therapy (CBT) as a means of treatment.

This review aimed to assess the effectiveness of all current treatments for people with delusional disorder. A search for randomised controlled trials was run in 2012. Authors found 141 citations in the search but only one trial, randomising 17 people, could be included in the review. The study compared the effectiveness of CBT with supportive psychotherapy for people with delusional disorder. Participants were already taking medication and this was continued during the trial. The review was not able to include any studies or trials involving medications of any type used to treat delusional disorder.

For the study that was included, there was limited information presented that we could use. Firm conclusions were difficult to make and no evidence on improving people's behaviour and overall mental health was available. More people left the study early from the supportive psychotherapy group, but number of participants was small and the overall difference between the groups was not enough to conclude one treatment was better than the other. A positive effect for CBT was found for people's social self esteem, although again, this finding is limited by the low quantity and quality of the data and does not relate to people's social or everyday functioning.

Currently there is an overall lack of high quality evidence-based information about the treatment of delusional disorders and insufficient evidence to make recommendations for treatments of any type. Until such evidence is found, the treatment of delusional disorders will most likely include those that are considered effective for other psychotic disorders and mental health problems.Further large-scale and high quality research is needed in this area. Research could be improved by conducting trials specifically for people with delusional disorder.

Ben Gray, Senior Peer Researcher, McPin Foundation. Authors' conclusions:
    Despite international recognition of this disorder in psychiatric classification systems such as ICD-10 and DSM-5, there is a paucity of high quality randomised trials on delusional disorder. There is currently insufficient evidence to make evidence-based recommendations for treatments of any type for people with delusional disorder. The limited evidence that we found is not generalisable to the population of people with delusional disorder. Until further evidence is found, it seems reasonable to offer treatments which have efficacy in other psychotic disorders. Further research is needed in this area and could be enhanced in two ways: firstly, by conducting randomised trials specifically for people with delusional disorder and, secondly, by high quality reporting of results for people with delusional disorder who are often recruited into larger studies for people with a variety of psychoses
    Delusional disorder is commonly considered to be difficult to treat. Antipsychotic medications are frequently used and there is growing interest in a potential role for psychological therapies such as cognitive behavioural therapy (CBT) in the treatment of delusional disorder.
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Re: Shared Delusional Disorder and its treatments

Post05 Feb 2016

Shared psychotic disorder


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.


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.DiagnosisA 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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