Folie à deux

- _This is about the mental disorder, the studio album is at Folie à Deux (album)_
***Folie à deux*** **(FaD)** is a type of mental illness. It is also called **induced delusional disorder** or **shared psychotic disorder**. It is a rare condition where two or more people in a close relationship share a specific delusion.

The name _folie à deux_ means "madness of two" in French. While most cases occur between two people, the condition can occur among three people (_folie à trois_), four people (_folie à quatre_), within an entire family (_folie en famille),_ or in a large group (_folie à plusieurs)._

Jules Baillarger first reported the condition in 1860. Ernest-Charles Lasègue and Jules Falret named it _folie à deux_ in an 1877 article_._

## Characteristics

In FaD, delusional beliefs are transferred from a psychotic person (called the primary, principal, or inducer) to another person (called the secondary, acceptor, or associate). The secondary person comes to believe that the primary person's delusions are real. The secondary person adopts those delusions; now both the primary and the secondary share the delusion. (This is why FaD is also called "shared psychotic disorder.")

### Prevalence

FaD generally develops between people who have lived together for a long time and are attached to each other. It usually occurs among family members, though there have been cases involving friends, families, physicians and patients, and even a dog.

In a study of all FaD cases reported between 1993-2005, almost all (98%) occurred within the nuclear family. Over half (52%) occurred between married or long-term couples. Another quarter (24%) occurred between sisters. Another study found that around 50% of cases occur either between sisters, or between mother and daughter.

### Primary & secondary

In many cases, there was already a difference in power between the primary and secondary even before FaD developed. In some cases - but not all - the secondary partner is younger than the primary partner, more passive, less intelligent, more trusting, and/or has lower self-esteem.

## Proposed types

In an important 1942 article, psychiatrist Alexander Gralnick listed four types of _folie à deux_. Each type involves the transfer of delusional beliefs from one person to another.

### _Folie imposée_

_Folie imposée_ means "imposed madness." In this type of shared psychosis, a person forms a delusion and passes it on to someone else (who might be younger and more submissive). If that secondary partner separates themselves from the psychotic person, their delusions usually disappear quickly. In Gralnick's study of 103 cases of _folie à deux,_ almost 60% were the imposed type.

### _Folie communiquée_

_Folie communiquée_ (communicated psychosis) is similar to _folie imposee._ In both types, a person forms a delusion and passes it on to the secondary partner. However, in _folie communiquée,_ the secondary partner resists the delusion for a long period before finally adopting it. Even if they are separated from the psychotic person, their delusions continue.

In Gralnick's study of 103 cases of _folie à deux,_ the communicated type was the second most common form of the disorder (with 24 cases).

### _Folie simultanée_

_Folie simultanée_ means "simultaneous madness." This condition involves two people who are already psychotic and have their own separate delusions. They influence each other, and their delusions become very similar.

### _Folie induite_

In _folie induite_ (induced psychosis), both the inducer and the secondary partner already have psychosis, and the secondary partner develops the inducer's specific delusions.

### Criticism

Newer studies seem to indicate that this classification may not be sufficient to fully describe _folie à deux_. Critics say there may be more symptoms than are usually described in the cases above. Also, in many cases, separating the two patients may not be enough to make the condition go  away in one of them. Also, the person described as "sane" before developing the folie à deux may already be suffering from a psychiatric illness, or may develop one.