Induced delusional disorder or folie a deux is characterized by the presence of similar delusional ideas in two or more individuals. The delusional system develops as a result of a close relationship with a person with an established psychotic disorder. Most commonly the affected persons are members of a family.

An unusual case of folie a famille involving four siblings, brother and three sisters, (folie a quatre) is presented. This case was detected in the context of a community-based psychiatric service in Greece, the Mobile Psychiatric Unit of the prefectures of Ioannina and Thesprotia.

A 46-year-old woman was referred from primary care physicians for the management of a psychotic exacerbation. On the examination it was revealed that she and her three older siblings were sharing the delusional idea of being affected by their neighbors with magic. These siblings had been living in social isolation for long and have been querulant and aggressive toward their neighbors, against whom they had undertaken a succession of lawsuits. None of the rest siblings accepted to be examined so it could not be determined who the inducer was or what the diagnoses were for each of the affected persons. The patient did not receive the prescribed medication and did not engage in follow-up.

Cases of induced delusional disorder may be difficult to be detected and treated. Mobile psychiatric units in co-operation with primary care physicians may have an opportunity to provide appropriate treatment for such patients in rural areas.