Shared psychotic disorder

Shared psychotic disorder, a rare and atypical psychotic disorder, occurs when an otherwise healthy person (secondary partner) begins believing the delusions of someone with whom they have a close relationship (primary partner) who is already suffering from a psychotic disorder with prominent delusions. This disorder is also referred to as "folie á deux."

In cases of shared psychotic disorder, the primary partner is most often in a position of strong influence over the other person. This allows them, over time, to erode the defenses of the secondary partner, forcing their strange belief upon them. In the beginning, the secondary partner is probably healthy, but has such a passive or dependent relationship with the primary partner that imposition of the delusional system is but a matter of time. Most of the time, this disorder occurs in a nuclear family. In fact, more than 95% of the cases reported involved people in the same family. Without regard to the number of persons within the family, shared delusions generally involve two people. There is the primary, most often the dominant person, and the secondary or submissive person. This becomes fertile ground for the primary (dominant) partner to press for understanding and belief by others in the family.

Shared psychotic disorder has also been referred to by other names such as psychosis of association, contagious insanity, infectious insanity, double insanity, and communicated insanity. There have been cases involving multiple persons, the most significant being a case involving an entire faamily of 12 people (folie á douze).

Symptoms 

The principal feature of shared psychotic disorder is the unwavering belief by the secondary partner in the dominant partner's delusion. The delusions experienced by both primary partners in shared psychotic disorder are far less bizarre than those found in schizophrenic patients; they are, therefore, believable. Since these delusions are often within the realm of possibility, it is easier for the dominant partner to impose his/her idea upon the submissive, secondary partner.

Diagnosis

A clinical interview is required to diagnose shared psychotic disorder. There are basically three symptoms required for the determination of the existence of this disorder:

• An otherwise healthy person, in a close relationship with someone who already has an established delusion, develops a delusion himself/herself.

• The content of the shared delusion follows exactly or closely resembles that of the established delusion.

• Some other psychotic disorder, such as schizophrenia , is not in place and cannot better account for the delusion manifested by the secondary partner.

Treatment

The treatment approach most recommended is to separate the secondary partner from the source of the delusion. If symptoms have not dissipated within one to two weeks, antipsychotic medications may be in order.

Once stabilized, psychotherapy should be undertaken with the secondary partner, with an eye toward integrating the dominant partner, once he/she has also received medical treatment and is stable.