Folie à deux


Folie à deux, also known as shared psychosis or shared delusional disorder, is a psychiatric syndrome in which symptoms of a delusional belief, and sometimes hallucinations, are transmitted from one individual to another. The same syndrome shared by more than two people may be called folie à... trois or quatre ; and further, folie en famille or even folie à plusieurs.
The disorder was first conceptualized in 19th-century French psychiatry by Charles Lasègue and Jean-Pierre Falret and is also known as Lasègue-Falret syndrome.
Recent psychiatric classifications refer to the syndrome as shared psychotic disorder and induced delusional disorder, although the research literature largely uses the original name. This disorder is not in the current DSM.

Signs and symptoms

This syndrome is most commonly diagnosed when the two or more individuals of concern live in proximity, may be socially or physically isolated, and have little interaction with other people.
Various sub-classifications of folie à deux have been proposed to describe how the delusional belief comes to be held by more than one person:
Folie à deux and its more populous derivatives are in many ways a psychiatric curiosity. The current Diagnostic and Statistical Manual of Mental Disorders states that a person cannot be diagnosed as being delusional if the belief in question is one "ordinarily accepted by other members of the person's culture or subculture." It is not clear at what point a belief considered to be delusional escapes from the folie à... diagnostic category and becomes legitimate because of the number of people holding it. When a large number of people may come to believe obviously false and potentially distressing things based purely on hearsay, these beliefs are not considered to be clinical delusions by the psychiatric profession and are labelled instead as mass hysteria.
As with most psychological disorders, the extent and type of delusion varies, but the non-dominant person's delusional symptoms usually resemble those of the inducer. Prior to therapeutic interventions, the inducer typically does not realize that they are causing harm but instead believe they are helping the second person to become aware of vital or otherwise notable information.

Type of delusions

Psychology Today magazine defines delusions as "fixed beliefs that do not change, even when a person is presented with conflicting evidence." Types of delusion include:
As with many psychiatric disorders, shared delusional disorder can negatively impact the psychological and social aspects of a person's wellbeing. Unresolved stress resulting from a delusional disorder will eventually contribute to or increase the risk of other negative health outcomes such as cardiovascular disease, diabetes, obesity, immunological problems, and others. These health risks increase with the severity of the disease, especially if an affected person does not receive or comply with adequate treatment.
Persons with a delusional disorder have a significantly high risk of developing psychiatric comorbidities such as depression and anxiety. This may be attributable to a genetic pattern shared by 55% of SDD patients.
Shared delusional disorder can have a profoundly negative impact on a person's quality of life. Persons diagnosed with a mental health disorder commonly experience social isolation, which is detrimental to psychological health. This is especially problematic with SDD because social isolation contributes to the onset of the disorder; in particular, relapse is likely if returning to an isolated living situation in which shared delusions can be reinstated.

Causes

No one knows what causes SDD exactly but stress and social isolation are the main contributors. When we are socially isolated the few people we do talk to become very important to us, and therefore they are seen as more trustworthy, so when an inducer is sharing their delusions, the second person is more likely to believe them. Additionally, since they are socially isolated, people developing shared delusional disorder do not have others reminding them that their delusions are either impossible or not likely, and are therefore more likely to develop SDD. In fact, the treatment for shared delusional disorder is for the person to be removed from the inducer and seek additional treatment, if necessary.
Stress is also a factor because it triggers mental illness. The majority of people that develop shared delusional disorder are genetically predisposed to mental illness; however this predisposition is not enough to develop a mental disorder. However, when that person becomes stressed their adrenal gland releases the stress hormone cortisol into the body which released increased levels of dopamine in their brain and changes in dopamine levels are linked to mental illness. As a result, stress puts one at a heightened risk of developing a psychological disorder such as shared delusional disorder.

Diagnosis

Shared delusional disorder is difficult to diagnose because usually, the afflicted person does not seek out treatment because they do not realize that their delusion is abnormal as it comes from someone in a dominant position who they trust. Furthermore, since their delusion comes on gradually and grows in strength over time, their doubt is slowly weakened during this time. Shared delusional disorder is diagnosed using the DSM-5 and according to this the person afflicted must meet three criteria:
  1. They must have a delusion that develops in the context of a close relationship with an individual with an already established delusion.
  2. The delusion must be very similar or even identical to the one already established one that the primary case has.
  3. The delusion cannot be better explained by any other psychological disorder, mood disorder with psychological features, a direct result of physiological effects of substance abuse or any general medical condition.

    Related phenomena

Reports have stated that a phenomenon similar to folie à deux was induced by the military incapacitating agent BZ in the late 1960s.

Prevalence

Shared delusional disorder is most commonly found in women with slightly above-average IQs who are isolated from their family, and are in relationships with a dominant person who has delusions. The majority of secondary cases also meet the criteria for which is characterized by a pervasive fear that leads them to need constant reassurance, support and guidance. Additionally, 55% of secondary cases had a relative with a psychological disorder that included delusions and, as a result, the secondary cases are usually susceptible to mental illness.
The disorder can also occur in cults to a serious extent; one example is Heaven's Gate, a UFO religion led by Marshall Applewhite, who had delusions about extraterrestrial life. The members of the cult developed the same delusion, and went on to commit suicide with the intention of their spirits joining an extraterrestrial spacecraft heading towards a comet.

Treatment

After a person has been diagnosed, the next step is to determine the proper course of treatment. The first step is to separate the formerly healthy person from the inducer and see if the delusion goes away or lessens over time. If this is not enough to stop the delusions there are two possible courses of action: Medication or therapy which is then broken down into personal therapy and/or family therapy.
With treatment, the delusions and therefore the disease will eventually lessen so much so that it will practically disappear in most cases. However left untreated it can become chronic and lead to anxiety, depression, aggressive behavior and further social isolation. Unfortunately there are not many statistics about the prognosis of shared delusional disorder as it is a rare disease and it is expected that the majority of cases go unreported; however, with treatment, the prognosis is very good.

Medication

If the separation alone is not working, antipsychotics are often prescribed for a short time to prevent the delusions. Antipsychotics are medications that reduce or relieve symptoms of psychosis such as delusions or hallucinations. Other uses of antipsychotics include stabilizing moods for people with mood swings and mood disorders, reducing anxiety in anxiety disorders and lessening tics in people with Tourettes. Antipsychotics do not cure psychosis but they do help reduce the symptoms and when paired with therapy, the afflicted person has the best chance of recovering. While antipsychotics are powerful, and often effective, they do have side effects such as inducing involuntary movements and should only be taken if absolutely required and under the supervision of a psychiatrist.

Therapy

The two most common forms of therapy for people suffering from shared delusional disorder are personal and family therapy.
Personal therapy is one-on-one counseling that focuses on building a relationship between the counselor and the patient and aims to create a positive environment where the patient feels that they can speak freely and truthfully. This is advantageous because the counselor can usually get more information out of the patient to get a better idea of how to help them if that patient feels safe and trusts them. Additionally if the patient trusts what the counsellor says disproving the delusion will be easier.
Family therapy is a technique in which the entire family comes into therapy together to work on their relationships and to find ways to eliminate the delusion within the family dynamic. For example, if someone's sister is the inducer the family will have to get involved to ensure the two stay apart and to sort out how the family dynamic will work around that. The more support a patient has the more likely they are to recover, especially since SDD usually occurs because of social isolation.

Notable cases