Shared Paranoid Disorder, also known as Folie à Deux, is a rare psychiatric condition characterized by the presence of a delusional belief shared by two or more individuals who have a close relationship or live in close proximity. This disorder is considered a subtype of Delusional Disorder and is classified under the category of Shared Psychotic Disorder in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).
Individuals affected by Shared Paranoid Disorder typically experience fixed, false beliefs (delusions) that are not influenced by rational arguments or evidence to the contrary. These delusions usually involve persecution, grandiosity, or a combination of both, and may revolve around various themes such as being spied on, being followed, or having special powers or extraordinary abilities.
What distinguishes Shared Paranoid Disorder from other types of delusional disorders is the transmission of the delusional belief from one primary individual to the other(s), resulting in it being held by all participants in the shared delusion. The secondary individual in the relationship or shared environment usually lacks any previously existing psychiatric illness, but in some cases may have a predisposition to developing delusional beliefs.
Treatment of Shared Paranoid Disorder typically involves a combination of psychoeducation, individual therapy, and medication. Separation of the affected individuals may be necessary in severe cases to break the cycle of the shared delusion. It is noteworthy to mention that the prognosis of Shared Paranoid Disorder can vary depending on factors such as the underlying relationship dynamics and the willingness of participants to engage in therapeutic interventions.