Folie a deux is French for “madness shared by two,” also know as a shared psychosis. This is a rare diagnosis in that it requires two individuals that live in close proximity to share delusions and/or hallucinations. These two people would normally live in isolation and have little contact with the outside world. A modern scenario of this would be people living away from civilization and firmly believing that the CIA or the government is spying on them and planning to harm them.