Q & A – Folie à deux

Shared psychosis, also known as folie à deux, is a rare psychiatric disorder in which two or more people share a delusional belief system. It is a form of psychosis in which symptoms of a delusional belief are transmitted from one individual to another. The disorder is characterized by the presence of a primary delusional disorder in one individual (the “inducer”) and the development of a similar delusional belief in another individual (the “follower”).

What problems do Folie à deux cause?

Folie à deux can cause a variety of problems, including:

1. Difficulty in distinguishing reality from fantasy: People with folie à deux may have difficulty distinguishing reality from fantasy, which can lead to confusion and difficulty in making decisions.

2. Social isolation: People with folie à deux may become socially isolated due to their shared delusions, which can lead to further psychological distress.

People with folie à deux may have difficulty forming relationships due to their tendency to become overly dependent on their partner. They may also struggle to trust others and may be overly suspicious of their partner’s motives. Additionally, they may be overly possessive and controlling, which can make it difficult for them to form healthy relationships. They may also struggle to maintain relationships due to their difficulty in communicating their feelings and needs.

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:^[7]

Folie imposée

Where a dominant person (known as the ‘primary’, ‘inducer’, or ‘principal’) initially forms a delusional belief during a psychotic episode and imposes it on another person or persons (the ‘secondary’, ‘acceptor’, or ‘associate’) with the assumption that the secondary person might not have become deluded if left to his or her own devices. If the parties are admitted to hospital separately, then the delusions in the person with the induced beliefs usually resolve without the need of medication.

Folie simultanée

Either the situation where two people considered to independently experience psychosis influence the content of each other’s delusions so they become identical or strikingly similar, or one in which two people “morbidly predisposed” to delusional psychosis mutually trigger symptoms in each other.