Induced delusional disorder (ICD-10) / Shared psychotic disorder (DSM-IV-TR) is characterized by delusional beliefs shared between 2 or more people with a close relationship. DSM-5 no longer separates delusional disorder from shared delusional disorder.

This case report aims to describe and discuss a case of shared delusional beliefs, providing an updated review on this disorder and other related conditions.

A psychiatric interview of a patient and a friend involved in the same delusional belief system was undertaken. A review of the literature namely in PubMed data base and Google Scholar with the key words 'Folie a deux/quatre”, 'induced delusional disorder” and 'shared psychotic disorder” was also conducted.

Case study of a 32-year-old woman with normal functioning assessed in the emergency room with the initial complaint of insomnia, in the context of a family conflict. During the clinical interview, grandiose delusional beliefs regarding angels and of self reference were elicited. These beliefs were found to be shared between the patient, a friend, a brother and a cousin. A clinical report and a diagnostic discussion were made, based on a bibliographic review.

Shared psychotic disorder is an uncommon variant of delusional disorder. Genetic and psychological factors may play an etiological role. This particular case involved 4 people, 3 family members and a close friend. Shared psychotic disorder is a diagnosis in transition, this report allows an update on changes brought in by DSM-5.