So long, we are acquainted with the term "shared psychotic disorder" or "induced psychotic disorder" which was first described by Lasegue and Falret (Lasegue C, Falret J 18:321) [1] in 1877 which is popularly known as "folie a deux.
Since the introduction of validated diagnostic criteria, very little has changed in the description of the phenomena, standardized criteria adopt two main terms "induced delusional disorder" (ICD-10) [7] and "shared psychotic disorder" (DSM-IV).