Shared psychotic disorder

Shared psychotic disorder also called Folie a deux (Folie à deux), is a rare delusional disorder shared by 2 or occasionally, more people who are in a close relationship ¹. Shared psychotic disorder usually occurs in a person or group of people (usually a family) who are related to a person with a significant delusional disorder or schizophrenia. The (inducer, primary psychosis) who has a psychotic disorder with delusions influences another individual or more (induced, secondary psychosis) with a specific belief ². The patient with the primary shared psychotic disorder is usually the socially dominant member in the relationship and imposes the delusion on or convinces the patient with the secondary disorder of the unusual beliefs. Identifying who in the relationship has the primary psychosis is important because the person with the secondary disorder typically does not maintain the delusional beliefs when separated from the person with the primary disorder ³. Shared psychotic disorder commonly presents among two individuals, but in rare cases can include larger groups, i.e., family and called folie a famille ⁴.

Shared psychotic disorder 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 ⁵. There could be other psychiatric features such as social withdrawal, hallucinations or suicidal thoughts ⁶. 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.

Gralnick ⁷ in his review of 103 cases of shared psychotic disorder 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:

• Folie imposee (imposed psychosis) – Described by Lasegue and Falret in 1877 ⁸. The delusions of a person with psychosis are transferred to a person who is mentally sound, both persons are intimately associated. These soon disappear once the two were separated. The mental status exam of both affected individuals would be significant for delusional thinking, lack of judgment and insight, poor attention and concentration, and affect may or may not be affected. Both individuals would be perseverative and sometimes preoccupied with limited relatedness.
• 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 genetic risk factors among siblings. The mental status exam of the affected individuals would be consistent with paranoia, lack of insight, disorganized thought processes in extreme cases, and lack of relatedness.
• Folie communiquée (communicated psychosis) – Described by Marandon de Montyel in 1881. The recipient develops psychosis after a long period of resistance and maintains the symptoms even after separation. The mental status exam may be consistent with hypervigilance, obsessive thinking, brooding, rumination, anxiety, and lack of reasoning.
• Folie induite (induced psychosis) – Described by Lehmann in 1885. In this type, new delusions are adopted by an individual with psychosis who is under the influence of another individual with psychosis. Researchers noticed that an expansion of the delusions exists. This type would be present among two mentally ill individuals. The mental status exam would be similar to one of a psychotic patient, namely, paranoia; lack of reasoning, judgment, and insight; and poor relatedness. Limited eye contact, bizarre mannerisms, and magical thinking may be apparent on assessment.

The first listing of shared psychotic 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 ⁹.

The incidence and prevalence of shared psychotic disorder are difficult to estimate, but the disorder appears to be rare. However, some studies report 1.7 to 2.6% of psychiatric hospital admissions ¹⁰. These figures could, however, be underestimated as it is under-diagnosed and often missed in clinical practice. Psychiatrists may treat the primary shared psychotic disorder while not being aware that the delusions exist in others ¹¹. Some authors even argue that shared psychotic disorder is not rare ¹². Females and males are equally affected.

Counseling and therapy can usually help people who have a shared psychotic disorder. Usually, the person with the psychotic symptoms needs pharmacologic treatment ³.

Shared psychotic disorder causes

The exact cause of shared psychotic disorder is still unknown ². 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 ¹².
• 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 ¹².
• 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 ¹³.
• 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 ¹⁴.
• 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 ¹².
• Cognitive impairment: It has been noted that the secondaries lack good judgment and intelligence ¹³.
• 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 ¹³.
• 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 ¹⁴.
• 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 ¹⁵.
• Age: Previous studies reported age differences. The elderly being a dominant while the young being submissive, but recent studies do not support this finding ⁹.
  Gender: It is more common among females to be part of this disorder, both as a primary or secondary ⁹.

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 ¹⁶. Some authors even emphasized the existence of a reversal role between partners due to the complexity of the shared psychotic disorder ¹⁵.

Shared psychotic disorder 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.

Shared psychotic disorder symptoms

Shared psychotic disorder cases are dependent on the type of delusion shared. People with psychosis experience an altered sense of reality. They have difficulty with the way they interpret the world around them, and their thinking can be confused. They may experience hallucinations, such as hearing voices that aren’t there, or delusions, where they have false beliefs about themselves or the world around them. 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 ¹¹.

A survey of the literature shows that most of those afflicted with the disease are women with higher intelligence quotient scores who are usually younger than their significant other (eg, partner, parent, sibling, friend). The survey further suggests that the primary patients are susceptible to schizophrenia and often are diagnosed with episodes of paranoid delusions.

Quite often, factors arise because of unhealthy or interrupted ego development during the early stages of life. As Freud suggested with his theories on the Oedipus and Electra complexes, children develop attraction to the opposite-sex parent, developing a greater sense of self by comparing and resisting identification with their same-sex male or female parent, recognizing that each is similar to or different from themselves ¹⁷. If the relationship between parent and child is filled with jealousy, rejection, or anger, or if the relationship becomes more sexual than that of a healthy parent-child relationship, symptoms of shared psychotic disorder generally express themselves.

The adult-child identifies inappropriately with the opposite-sex parent and often perceives or has delusions of shared sexual intimacy with the parent. The person who has the disorder tends to form symbiotic relationships with a significant other who shares a common psychiatric disorder; often, they too are susceptible to unhealthy bonding, lowered self-esteem, and lack of personal responsibility that would otherwise foster healthy interdependence within intimate relations.

Studies of individual cases have shown that delusional ideas and psychotic symptoms are rarely transmitted to a healthy individual whose partner displays unhealthy behavior resulting from a psychotic disease; however, a passive person may have a genetic predisposition to psychosis and, as a result, may develop shared psychotic disorder ¹¹.

Shared psychotic disorder complications

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 ¹¹.

Shared psychotic disorder diagnosis

Most of the investigations whether imaging studies 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.

DSM-4 Shared Psychotic Disorder (Folie à deux) ¹⁸:

• A) A delusion that arises in a person in the context of close relationships with other people, or some people, with pre-existing delusions
• B) Similar delusions relate to their contents with people who already have this delusion
• C) Disorders are not better calculated by other psychotic disorders (for example, schizophrenia) or mood disorders with psychotic features and not due to direct physiological effects of substances (for example, substance abuse and drugs) or general medical conditions

ICD-10 diagnostic criteria for shared psychotic disorder (Induced Delusional Disorder) is as follows ¹⁹:

• Two people share the same delusion or delusional system and support one another in this belief.
• They have an unusually close relationship.
• Temporal or contextual evidence exists that indicates the delusion was induced in the passive member by contact with the active partner.

Shared psychotic disorder treatment

Shared psychotic disorder treatment should be tailored case by case. 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 ²⁰.

Psychotherapy could be offered to both partners either individually or as conjoined-psychotherapy ¹⁵.
Electroconvulsive therapy (ECT) has also been an option ¹².

Treatment with medication for both partners whether alone (antipsychotics-antidepressant) or in combination (mood stabilizers/antipsychotics) and (antidepressants/antipsychotics) could improve the condition ¹². Those started on medications indicate that their condition is severe and likely to express residual symptoms.

The new standard of treatment for shared psychotic disorders includes the use of 2 agents. The atypical newer neuroleptics are the accepted mode of treatment for the spectrum of these disorders. Newer-generation anticonvulsants are also highly effective. Aripiprazole (Abilify) and quetiapine (Seroquel) are extremely effective in these cases ²¹.

Initiation of aripiprazole at 5-10 mg oral once daily with a titration upward by 5-10 mg oral every 3-5 days until a 25-60 mg oral once daily dosage is achieved should thwart and alleviate the symptoms of the psychoses. Quetiapine is initiated at 25-50 mg oral twice daily and increased by 50 mg oral twice daily every 3 days until symptom resolution is achieved. Maintenance doses of 200-600 mg can be achieved easily.

It is critical follow up with cases because of a possible alternative diagnosis.

Shared psychotic disorder prognosis

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 ¹⁶.

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