Shared psychotic disorder, also known as folie à deux, is a rare psychiatric condition in which a delusion is transmitted from one individual (the primary case) to another individual (the secondary case) who has a close relationship with the primary case. The secondary case comes to believe in the delusion and starts experiencing similar or identical delusional beliefs as the primary case.
The delusion in shared psychotic disorder can be on any subject and is usually consistent with the delusion of the primary case. For example, if the primary case believes they are being persecuted by a secret organization, the secondary case will also develop the belief that they are being targeted by the same group. The content of the delusion may vary widely depending on the specific circumstances and the nature of the relationship between the two individuals.
Shared psychotic disorder is considered rare and usually occurs in close relationships, such as family members, spouses, or very close friends, where there is a high degree of emotional and psychological intimacy. The secondary case often lacks a significant independent history of psychiatric illness but develops the delusion due to their close association with the primary case.
It's important to note that shared psychotic disorder is a diagnosis made by mental health professionals, and it requires a thorough evaluation of both individuals involved to differentiate it from other psychiatric conditions with similar symptoms. Treatment typically involves addressing the underlying issues and may include medication and psychotherapy for both individuals involved.