Shared Psychotic Disorder

Shared Psychotic Disorder

Article Author:
Feras Al Saif
Article Editor:
Yasir Al Khalili
8/10/2020 4:18:42 PM
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Shared Psychotic Disorder


Shared psychotic disorder (Folie a deux) is an unusual mental disorder characterized by sharing a delusion among two or more people who are in a close relationship. The (inducer, primary) who has a psychotic disorder with delusions influences another individual or more (induced, secondary) with a specific belief. It commonly presents among two individuals, but in rare cases can include larger groups, i.e., family and called folie a famille.[1][2]

Baillarger was the first to report this condition in 1860. During the 19th century, psychiatrists in Europe suggested different names for this condition. In France, it has been called "folie communiquee"(communicated psychosis) by Baillarger. In German-speaking psychiatry, named "Induziertes Irresein" by Lehman and Sharfetter.  In 1877 Lasegue and Falret coined the term “folie a deux” and described this syndrome. The French word “folie à deux" means madness shared by two. The concept by itself highlighted that the delusional idea could be shared among two closely associated individuals or more. Gralnick in his review of 103 cases of folie à deux described four types of this disorder. He defined it as a psychiatric entity characterized by the transfer of delusions and/or abnormal behavior from one person to one or several others who have a close association with the primarily affected patient. The types are the following:

  1. Folie imposee (imposed psychosis) - Described by Lasegue and Falret in 1877. The delusions were transferred from one individual to another with the existence of an intimate relationship. These soon disappear once the two were separated.
  2. Folie simultanee (simultaneous psychosis) - Described by Regis in 1880. Both partners shared the psychoses simultaneously. They both have risk factors through long social interactions that predispose to develop this condition. There are reports of sharing genetical risk factors among siblings.
  3. Folie communiquée (communicated psychosis) - Described by Marandon de Montyel in 1881. This type is similar to type (1) however more resistance is applied to the delusions by the second partner. Finally, the second partner will adopt it even after separation.
  4. Folie induite (induced psychosis) - Described by Lehmann in 1885. In this type, additional new delusions induced to the second partner by the first partner. Researchers noticed that an expansion of the delusions exists. This type would be present among two mentally ill individuals.

The first listing of this disorder in DSM-III was shared paranoid disorder, but in the later edition (DSM-IV) the term changed to shared psychotic disorder. However, in the latest edition, DSM-5, it was moved under other specified schizophrenia spectrum and other psychotic disorder. ICD-10 listed it as Induced delusional disorder.[2]


The exact cause of shared psychotic disorder is still unknown. However, certain risk factors associated with it include:

  • Length of a relationship: Numerous studies highlight the role of the long relationship duration as an essential factor for developing this condition. It is crucial to understand that the attachment with the primary case plays a key role in adopting the delusion.[3]
  • Nature of the relationship: The majority of cases reported were among family members. The commonest relationship was between married or common-law couples and the second most common group was between sisters.[3]
  • Social Isolation: Most cases reported poor interaction with society. An individual who is confused and perplexed can undergo influence under frightening conditions in the absence of social comparison. This information received by the secondary individual is in harmony with what the primary individual felt. The conviction to certain ideas will eventually prevail as the only solution to maintain a mutual relationship.[4]
  • Personality disorder: Individuals usually show features of a personality defect. The usual description for them is as neurotic, introvert, and emotionally immature. Some case reports noticed features of premorbid personality disorders especially dependent(passive), schizoid and schizotypal.[5][6]
  • Untreated Mental Disorder in the primary: An untreated individual with chronic mental conditions could be a social risk factor of influence to the other partner or family. The commonest diagnosis in the primary is a Delusional disorder followed by schizophrenia and affective disorder.[3]
  • Cognitive impairment: It has been noted that the secondaries lack good judgment and intelligence.[4]
  • Comorbidity of the secondary: An individual diagnosed with a mental disorder, i.e., schizophrenia, bipolar affective disorder, depression, dementia or mental retardation carries a risk to be influenced by another mentally ill.[4]
  • Life events: Stressful life events that affect the relationship could influence behavior in the individual to accept certain delusions or lessening the ability to resisting the feelings/emotions. An example could be a wife who is suffering from delusions for several years accusing her husband who has erectile dysfunction of being in a relationship with a mistress or that the mistress is “stimulating him with Viagra and narcotics.” He will eventually accept this belief taking into account the unstable passive personality condition, as well as the serious situation from which he suffers.[5]
  • Communication difficulties: Having difficulties in sharing ideas could be a reason for preferring isolation. It is suggested that improving communication among dyad relationship through multiple-conjoint psychotherapy may help both partners understand the different point of views that will collapse in the presence of rigid mindless thinking.[7]
  • Age: Previous studies reported age differences. The elderly being a dominant while the young being submissive, but recent studies do not support this finding.[2]
  • Gender: It is more common among females to be part of this disorder, both as a primary or secondary.[2]


The incidence and prevalence of this condition are difficult to estimate. However, some studies report 1.7 to 2.6% of psychiatric hospital admissions.[8] These figures could, however, be underestimated as it is under-diagnosed and often missed in clinical practice. Psychiatrists may treat the primary while not being aware that the delusions exist in others.[9] Some authors even argue that the disorder is not rare.[3]


The condition is usually chronic and both the dominant and submissive individual share the original delusions. The sharing of delusions occurs under unique circumstances. The shared delusions could be of any type. There are racial variations. The common types of delusions are persecutory, followed by grandeur. In Japanese communities, persecutory delusions were the commonest followed by religious delusions.[4][10] There could be other psychiatric features such as social withdrawal, hallucinations or suicidal thoughts.[11] The functionality is generally preserved compared with other disorders. There may be significant impairment in a particular aspect of life. When the delusions are not confronted, the person cannot maintain a normal lifestyle.

The concept of the dominance-submissive relationship derived from the psychodynamic theory. The role of the primary is rigid and possessing a dominant role in the relationship while the submissive being less intelligent, passive, less resilient to suggestions, isolated and physically handicapped. [6] Some authors even emphasized the existence of a reversal role between partners due to the complexity of the disorder.[7]

History and Physical

Cases are dependent on the type of delusion shared. One partner usually faces a problem in the society that involves the intervention of a psychiatrist. Often, this problem is supported or under the influence of the other partner. Both exhibit unrealistic fixed false beliefs which are unshakable. They might be paranoid, fearful and suspicious of a neighbor or someone in their community. One might seek mental assessment after risky behavior, unreal claims, or recent assault. The secondary partner could be mistakenly referred and usually discovers that other people within his/her social sphere share the same belief as the primary. There could be under-treated or even undiagnosed cases within the community that last for several years before being discovered. Sometimes partners who shared particular delusions could be admitted inside the hospital together because of risky behavior or assault to themselves or others.

General description: The couples usually looking decent, well dressed and groomed.

Behavior: Defensive attitude or angry behavior could result in the patient towards an interviewer who challenges his/her delusions.

Speech: The speech is usually coherent and relevant.

Mood/Affect: Mood is usually congruent with the delusion; a paranoid patient may be irritable, while a grandiose patient may be euphoric.

Thought: The form of thought is usually directly goal oriented. The delusions are shared either entirely or partially, often not bizarre in content and are gradually systematically structured, overvaluing social/cultural/religious beyond the usual community norms or the presence of homicidal or suicidal plans.

Perceptions: They are less likely to express abnormal perceptions unless there are predisposing factors. Sometimes the secondary is the only person who experiences a form of hallucinations.

Orientation and Cognition: The patient usually oriented to time, place and person, unless being driven by his delusion. Memory and cognition are generally not affected.

Risks: It is crucial to evaluate the patient for suicidal or homicidal ideations and plans. If there is a history of aggression with adverse outcome, then hospitalization should be considered.

Insight and judgment: Most commonly patients and their partner have no insight regarding their mental illness. Judgment is assessable by questioning the history of past behavior and a future plan.[9][12][13]


As with any other psychiatric disorders, no specific labs are necessary for shared psychotic disorder.  Most of the investigations whether Imaging or laboratory tests should be considered to rule out any organic causes. A urine toxicology screen is vital to rule out any substance-induced conditions. If there are no medical/substance-induced condition, a full assessment should is next. It would be helpful to ask for collateral history about both partners from a third person. It is common to take history only from one of the partners because of strict social isolation situation; this would carry a great challenge for the psychiatrist. After taking a history, the psychiatrist should conduct a complete mental state examination. Collecting further details from other members of the family or friends should help in evaluating the case. The primary partner can be defensive and misleading leading to encapsulate the delusion; this will hide the symptoms for years unless s/he was acting on it.

Treatment / Management

Treatment should be tailored case by case. If there is an under-treated case, efforts should encourage increased adherence to the treatment plan. There have been suggestions that separation from the primary improves the condition significantly. After admission, the influence of the primary partner gradually disappears. It is worth noting, however, that recent data suggest that separation by itself could be insufficient or may aggravate the condition.[3][14] Treatment with medication for both partners whether alone (antipsychotics-antidepressant) or in combination (mood stabilizers/antipsychotics) and (antidepressants/antipsychotics) could improve the condition.[3] Those started on medications indicate that their condition is severe and likely to express residual symptoms. It is critical follow up with cases because of a possible alternative diagnosis. Psychotherapy could be offered to both partners either individually or as conjoined-psychotherapy.[7] ECT has also been an option.[3]

Differential Diagnosis

The differential diagnosis could be ruled out based on the history of the association between both partners. The onset of the condition usually precedes the onset of the shared delusions. The diagnosis of shared psychotic disorder should always only be made after ruling out any organic causes or substance induced.

  • Schizophrenia/Schizoaffective: This could be differentiated if the case reported other findings that are not being influenced by the primary, i.e., hallucinations, disorganized speech, grossly disorganized or negative symptoms. In the case of schizoaffective, an affective component should be present.
  • Mood Disorder with Psychotic features: THis condition has a specific delusion which is mood congruent and not shared but expressed independently.

In case that the delusions do not disappear when the partners are separated, it is important to reassessment and consideration for an alternative diagnosis.


The prognosis of shared psychotic disorder is challenging to estimate, as it depends on multiple risk factors including the primary mental disorder and the secondary biopsychosocial predisposing factors. Theoretically, children are more likely to benefit from separation than adults. The adherence on management plan in both partners could provide a better outcome than being untreated. The assessment of nature or the duration of exposure to the delusion could provide clues on the outcomes of the disorder. Having premorbid personality features or predisposing risk factors could complicate the condition leading to consider an alternative diagnosis.[6]


The patients are not discovered easily due to lack of insight. They are usually referred after a complication, namely acting on such delusions that jeopardize their life or others. for example, a patient acts on his/her paranoid delusions through multiple accusations or commits an assault. Having delusions of grandeur or religious delusions could cause a hazard to others.[9]

Enhancing Healthcare Team Outcomes

Patients with shared psychotic disorder could be undiagnosed because only the primary partner gets registered for treatment in a classical presentation. The level of tolerance and harmony among the two patients both could add a significant challenge to the clinician to identify every partner's role. Awareness is necessary regarding the nature of the dyad relationship dynamics and to manage it extensively. Most patients lack insight, which causes a substantial barrier to early discovery and management. The failure to adhere to treatment is an additional challenge to the clinician. A key aspect is to understand the impact of the delusions on both partner’s life. A board-certified psychiatric pharmacist should work with the team to select the best agents for optimal therapeutic results with minimal adverse effects. A holistic approach that assesses and manages the biopsychosocial factors should help for a better outcome. The psychotherapist, mental health nurse, and psychiatrist should continue to follow these patients as relapse is common due to noncompliance with treatment.

Shared psychotic disorder requires a comprehensive interprofessional team approach, that includes physicians, specialists, specialty-trained nurses, and pharmacists, working and communicating together in a team approach to lead to optimal treatment and outcomes. [Level V]

(Click Image to Enlarge)
The four types of Shared Psychotic Disorder (Folie à deux) by Alexander Gralnick (1942)
The four types of Shared Psychotic Disorder (Folie à deux) by Alexander Gralnick (1942)
Illustrations are contributed by Feras Al Saif, MBBCh


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