Shared Psychosis

Shared psychosis or Folie à deux is a psychiatric syndrome in which symptoms of a delusional belief and sometimes hallucinations are transmitted from one individual to another. In one famous case where shared insanity was seen was of Ursula and Sabina Eriksson, who were Swedish twin sisters visiting the UK. When Ursula ran into oncoming traffic due to delusions, her sister duplicated her actions and stepped into the path of an oncoming car. When they were released from the hospital, Sabina acted erratically and stabbed a man to death.