Folie à Deux Law and Legal Definition
Folie à deux is the French for “madness shared by two.” Folie à deux is a rare psychiatric syndrome in which there is simultaneous occurrence of symptoms of a mental disorder (as delusions) in two persons who are closely related as siblings or man and wife. The delusional belief or paranoia is transmitted from one individual to another. When the same syndrome is shared by more than two people it may be called folie à trois, folie à quatre, folie en famille or even folie à plusieurs ("madness of many").
Recent psychiatric classifications refer to the syndrome as shared psychotic disorder or induced delusional disorder.