BASICS
DESCRIPTION
- Shared delusional disorder occurs when a delusional belief held by one person (the "primary " ) becomes shared by one other (the "secondary " ) or several other people associated with that person. In most cases, a second person depends on, or has a passive relationship with, the primarily affected person. It is sometimes difficult to determine who is the primary and who is the secondary. The individuals involved are usually close and may be isolated from others.
- By definition, the shared belief, in order to be considered delusional, is one that is not generally accepted within the person 's culture. As a result, this illness exists along a spectrum: The least severe form being a shared "overvalued idea " (those holding it will relinquish it if given evidence to the contrary), the most severe form being a shared psychosis (attempts to disprove or cure patients of their delusions feels threatening to them).
- Shared delusional disorder is also known as shared psychotic disorder, folie a deux (if two people are involved), or folie a plusieurs (if several are involved). It was first described by two 19th-century French doctors, Ernest-Charles Lasegue and Jean-Pierre Falret, who believed that understanding a patient 's family relationships was key to the diagnosis and treatment of maladies mentales. Per the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5), all people involved would be diagnosed with a "delusional disorder " " so for diagnostic labeling purposes, there is no differentiating between the first person to have the belief and the subsequent ones. For treatment purposes, however, the differentiation could be important (see "Treatment " in the following discussion). Although "shared paranoid disorder " is no longer a stand-alone diagnosis, it can be a useful definition clinically and can be coded as paranoid disorder, shared (as a modifier).
- Concealment within the dyad (of the person with primary delusions and the one who comes to share it) is very common in this illness, and so it is difficult for clinicians to recognize it. The classic work "Paranoia and Paranoid States " (in the 1978 edition of The Harvard Guide to Modern Psychiatry) suggests that if health care providers can create a safe emotional space for patients, they may be able to reveal their delusions. Semrad and Day suggest that providers who take care of mentally ill patients thoroughly and painstakingly examine patients ' familial relationships to get clues about the losses in their lives that could be fueling delusions. The authors suggest that helping patients recognize their losses and supporting them through this process may help them break free of the delusions.
EPIDEMIOLOGY
Prevalence
- "Shared ideas " are more common than "shared psychoses. "
- Recently, researchers have found that these phenomena, considered very rare, may occur more often than is thought. First, a literature review of 20 years of case reports showed that the secondary often had a personal or family history of mental illness him-/herself. It concluded that Lasegue and Falret 's definition of the disease as a relationship between a "mentally ill " person and a "mentally well " person is probably too narrow a definition. It makes the further point that an exacerbation of symptoms between two (or more) mentally ill people is not uncommon (1). Second, the experience of paranoia includes the fear of being discovered, so patients affected by the illness would be less likely than those with other mental disorders to discuss it. Third, clinicians often see only one person of the ill dyad (or triad), which might prevent clinicians from discovering that illness also exists in someone close to the patient they are already treating.
- Case reports out of India argue for a further expansion in the consideration of who might be involved " citing reportedly new onset delusions among the primary (who had undergone a trauma) which come to influence family members around them. The set of case reports seemed to show that the primary could have been (or at least seemed) mentally well (2).
ETIOLOGY AND PATHOPHYSIOLOGY
- ≥1 persons may come to share in an individual 's delusions or paranoia, most commonly in cases in which those involved are isolated and emotionally close, and the secondary person(s) is (are) psychologically "vulnerable " " and may have personal or family histories of mental illness (diagnosed or not yet diagnosed).
- A group of people may adopt a delusional belief that those outside of the group are a threat or "evil " and so violence against those outside the group can be condoned. Psychohistorian Robert Jay Lifton, MD, says these "atrocity-producing situations " occur when the group is encouraged to adopt a leader 's ideals to combat their own sense of powerlessness.
RISK FACTORS
A major risk factor for a second person (or several people) to develop a delusional disorder is to have a close family member (the primary person affected) with a psychiatric diagnosis of schizophrenia, mood disorders, or delusions. The primary family member is usually a spouse or sibling and lives with the person who will come to share the delusions (3).
GENERAL PREVENTION
Adequate treatment for the primary person with mental illness, family therapy for those close to the primary, and bringing such families out of their isolation can help address major risk factors for the development of shared delusional/paranoid disorder.
COMMONLY ASSOCIATED CONDITIONS
- Familial mental illness
- Immigration/displacement from home
- Massive trauma
- Hearing (or other sensory) loss, which can lead to misinterpretation of outside phenomena
- Shared use of medications, drugs, or herbs that can stimulate hallucinations or changes in perception
- The secondary often suffers from dependent personality disorder (3), an all-consuming need to be taken care of that leads to submissive behavior and fear of separation (4).
DIAGNOSIS
HISTORY
- For the primary: may be a history of lack of parental contact leading to feelings of deprivation or excess family strife, in turn leading to emotional overload. A child in such an environment may use denial or distortion to cope.
- For the primary: history of mental illness, organic brain disease, dementia, or stroke
- For the primary and secondary who share the delusion: history of immigration, trauma (psychic, catastrophic), shared hallucinogen use, isolation
- For the group: history of powerlessness, shame, untreated trauma due to personal loss
- When taking a history, the clinician may observe that these patients appear alert, oriented, and outwardly able to function. However, their insight into their illness is poor and they rarely seek treatment on their own. They may challenge the clinician and resist any suggestion that their delusions are not true.
PHYSICAL EXAM
- Rule out physical causes for delusions in the primary or secondary, for example:
- Dementia, stroke, or organic brain disease, such as Huntington or Niemann Pick disease (use the Mini Mental Status Exam and a general neurologic exam)
- Signs of substance abuse (e.g., gum recession and nasal septum perforation in chronic cocaine use, gum recession in marijuana use, skin lesions and tooth decay in methamphetamine use)
- Endocrine disorders: Hypothyroidism, hyperthyroidism, hypercalcinosis, DKA, and hypoglycemia can lead to psychosis.
- Infection: syphilis, meningitis, HIV, parasites (e.g., neurocysticercosis with taenia solium, the "pork tapeworm " )
- Nutrition: vitamin B12, thiamine deficiency
- Poisoning: copper (Wilson disease), lead (environmental), zinc (e.g., from excess use of dental adhesives), insecticides (DEET)
- Mental status exam: typical findings include:
- Attitude: uncooperative, guarded
- Speech: fluid, coherent
- Mood: may be angry with clinician, frightened; as the delusion decreases: deep sadness or anger
- Affect: nonabile, incongruent to illness
- Thought content: includes the delusional system
- Thought process: linear
- Sensorium: alert
- Cognition: memory intact
- Insight and judgment: poor in the specific area of delusions, may be intact elsewhere (5)
DIFFERENTIAL DIAGNOSIS
- A shared cultural or cherished belief
- A paranoid reaction to a shared social upheaval, such as trauma associated with immigration, war, criminal violence, or natural disaster. For when example, the 1518 "plague " of St. Vitus dance, thought to involve hundreds of people in Strasbourg, France, is theorized to have been a stress-induced psychosis brought on by years of smallpox deaths and economic collapse and starvation. In 2014, villagers in the African country of Guinea attacked and killed eight members of an aid group, who had journeyed to their village to educate them about the Ebola virus. This was one of multiple attacks on aid workers and health care workers during the epidemic by villagers who believed the workers were causing the deadly hemorrhagic virus.
- Massive psychic trauma or complex trauma
- Pathologic grief
- Shared substance abuse or medication use leading to psychosis
- Mental illness, organic brain disease, infection, endocrine imbalance, nutrient or micronutrient imbalance, or poisoning in a primary person leading to psychosis or delusions comes to be shared by a secondary person who lives with, or is extremely close to the primarily affected person.
- Schizophrenia, which usually includes a thought disorder, impaired cognition, hallucinations, and poor social functioning (which are usually not present in delusional disorders although the delusions can lead to impairments in function)
- Keep in mind that an unlikely event believed to be "true " by ≥2 people may actually be true, and thus is not a delusion.
DIAGNOSTIC TESTS & INTERPRETATION
- Definitive diagnosis is usually made by a mental health clinician. A primary care provider can assist in the diagnosis and treatment by ruling out the other medical causes for psychosis (see "Physical Exam " ) and enabling patients to seek mental health help. This may be particularly difficult in cases of shared delusional disorder, as a hallmark of the disorder is that patients are in denial about the problem.
- Primary care clinicians may be able to support engagement in mental health treatment, if they state that the mental health professional can help alleviate the patient 's "discomfort. " As in any case of referral from primary care to mental health, the primary care clinician can deal with a patient 's possible feeling of embarrassment or abandonment by stating that mental illness is an illness like any other, that it is treatable, and that the primary care clinician will continue to be part of the patient 's care team during mental health treatment.
- To rule out other causes of psychosis (see "Physical Exam " )
Initial Tests (lab, imaging)
- Urine toxicology screen (for substances of abuse that can lead to changes in mental status); screening for heavy metal poisoning; serum studies to screen for the disorders mentioned in "Physical Exam "
- To rule out medical causes of psychosis (see "Physical Exam " )
TREATMENT
- First, explore whether the primary and secondary should be separated: If they are willing to be treated, if their relationship is benign, consider treating them together. Also assess whether each is so vulnerable that separating them would lead to more harm than keeping them together. However, if the relationship is volatile, dangerous, sadomasochistic, or presents a roadblock to treatment, the primary and those he/she is affecting need to be separated.
- Encourage patients to create an autobiography and a family biography to see if there is trauma being transmitted across generations.
- The psychotherapeutic approach includes focusing on the patient 's emotional troubles, frustrations, and difficulties with relationships with others and not challenging the patient 's delusional system or its contradictions. A therapeutic alliance should first be formed to help get the patient into treatment (5).
- Primary care clinicians may want to consider getting advice from, or referring such patients to, psychiatrists or therapists.
- For those involved in group delusions/psychoses: Therapies for those who have experienced trauma, which can include supportive therapy or movement therapies. Treatments that enhance empathy can follow.
MEDICATION
Treat the underlying disorder of the primary person experiencing the delusion. The secondary person may need also to be treated symptomatically with antipsychotics if separation and psychotherapy are not successful by themselves. Consult a psychiatrist before initiating psychotropic medical treatment.
ISSUES FOR REFERRAL
- Psychiatry for definitive diagnosis, psychotherapy, and evaluation of the need for antipsychotic medication
- Social work/psychotherapy to address family dynamics and stressors
- Law enforcement in cases of child/elder/incompetent dependent abuse or neglect
ADDITIONAL THERAPIES
Family therapy or group therapy to address the family/group stress and pathology that set the stage for the illness
COMPLEMENTARY & ALTERNATIVE MEDICINE
Intervention of healers specific to the patient 's culture. They can offer a reality "correction " to patients and cultural perspective to clinicians.
INPATIENT CONSIDERATIONS
- For initial stabilization, if needed, to help separate the person(s) with the secondary delusion from the person with the primary delusion
- For safety, for delusions that involve suicidality or homicidality
Discharge Criteria
Once psychiatrically stable and follow-up treatment is established
ONGOING CARE
- Psychotherapy
- Involvement of care professionals to support the family (or group) involved and try to lessen social isolation
- Legal involvement if a child/elder/incompetent adult has been victimized
FOLLOW-UP RECOMMENDATIONS
See "Ongoing Care " section.
PATIENT EDUCATION
Skillful psychotherapy may eventually allow patients to understand the underlying stresses that allowed the paranoid/psychotic ideas to take shape. When patients are properly supported through this process, their delusional system may recede.
PROGNOSIS
- Prognosis is good for recovery if treatment includes ongoing psychotherapy for both (or all) patients, separation of primary from the secondary (if it was deemed necessary), and social service support (3).
- It is more problematic if the belief system is supported by a larger ideology (e.g., witchcraft cults).
COMPLICATIONS
Self-harm or harm to others based on the contents of the shared delusional system
REFERENCES
11 Arnone D, Patel A, Tan GM, et al. The nosological significance of Folie Deux: a review of the literature. Ann Gen Psychiatry. 2006;5:11.22 Booth JH. Shared psychotic disorder. In: Encyclopedia of Mental Disorders. www.minddisorders.com/Py_Z/Shared-psychotic-disorder.html. Accessed July 5, 2010.33 American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed. Arlington, VA: American Psychiatric Association; 2013.44 Gutheil TG, Bursztajn H. Clinicians ' guidelines for assessing and presenting subtle forms of patient incompetence in legal settings. Am J Psychiatry. 1986;143(8):1020 " 1023.55 Ghosh P. Shared delusional disorder: a case report of folie a trios. Folie a trois. Eur J Psychol Educ Studies. 2014;1(1):36 " 40.
ADDITIONAL READING
- Lifton RJ. Witness to an Extreme Century: A Memoir. New York, NY: Free Press; 2011.
- Manschreck TC. Delusional disorder and shared psychotic disorder. In: Sadock BJ, Sadock VA, eds., Kaplan & Sadock 's Comprehensive Textbook of Psychiatry, 7th ed., vol. 1. Philadelphia, PA: Lippincott Williams & Wilkins; 2000:1243 " 1264.
CODES
ICD10
- F24 Shared psychotic disorder
- F22 Delusional disorders
ICD9
- 297.3 Shared psychotic disorder
- 297.1 Delusional disorder
SNOMED
- Induced psychotic disorder
- delusional disorder (disorder)
CLINICAL PEARLS
- Rule out medical causes for psychosis.
- Be aware that delusions occur along a continuum, from a cherished or cultural belief to a pathologically adopted belief system that isolates and may endanger.
- Clinicians should engage the patient by first empathizing with the pain and confusion that may underlie the adoption of a delusional belief system, rather than by initially challenging the belief system directly.
- Concealment within the dyad (of the person with primary delusions and the one who comes to share it) is very common in this illness, and so it is difficult for clinicians to recognize it. Providers who take care of mentally ill patients examine patients ' familial relationships to get clues about the losses in their lives that could be fueling delusions. Helping patients recognize their losses and supporting them through this process may help them break free of the delusions.
- Psychiatric, social work, and (in some cases) legal referral or monitoring (when minors, the elderly, or incompetent persons are involved) will likely be necessary.