Shared Psychotic Disorder

A delusional disorder shared by two or more people with close emotional links. Only one of the people suffers from a genuine psychotic disorder; the delusions are induced in the other(s) and usually disappear when the people are separated.
 
An individual diagnosed with other psychotic disorder (shared) needs to meet all of the following criteria:
  • Has symptoms of a psychotic disorder that cause clinically signficant distress or impairment in social, occupational, or other important areas of functioning predominate but do not meet the full criteria for any of the disorders in the schizophrenia spectrum and other psychotic disorders diagnostic class.
  • Shared delusional symptoms induced by a delusional, dominant partner: In the context of a relationship, the delusional material from the dominant partner provides content for delusional belief by the individual who may not otherwise entirely meet criteria for delusional disorder.
This is a delusional disorder in which one "genuinely" delusional person induces the same delusion in another person. The two individuals are in a close relationship (e.g., mother-child, or sibling-sibling). The "induced" delusions usually disappear when the delusional pair are separated. The "genuinely" delusional person usually has schizophrenia, delusional disorder or psychotic major depressive disorder. This disorder is not due to schizophrenia, a drug, medication, or other medical disorder.

Source and Credits: Mental Health