Folie à deux, shared psychosis,[2] or shared delusional disorder is a psychiatric syndrome in which symptoms of a delusional belief and sometimes hallucinations[3][4] are transmitted from one individual to another.[5] The same syndrome shared by more than two people may be called folie à trois, folie à quatre, folie en famille (“family madness”), or even folie à plusieurs (“madness of several”).
Tromp family: The mystery of a tech-free road trip gone wrong – BBC World News Australia
A family of five disappeared on a tech-free road-trip only to turn up one by one after a week-long odyssey of more than 1,600km (995 miles), which ended with a police investigation and two of them in psychiatric care. This was a missing person mystery that held Australia spellbound, writes Trevor Marshallsea.