Folie à deux (literally, "a madness shared by two") is a rare psychiatric syndrome in which a symptom of psychosis (particularly a paranoid or delusional belief) is transmitted from one individual to another. The same syndrome shared by more than two people may be called folie à trois, folie à quatre, folie à famille or even folie à plusieurs (madness of many). Recent psychiatric classifications refer to the syndrome as shared psychotic disorder (DSM-IV) (297.3) and induced delusional disorder (folie à deux) (F.24) in the ICD-10, although the research literature largely uses the original name.
This syndrome is most commonly diagnosed when the two or more individuals concerned live in close proximity and may be socially or physically isolated and have little interaction with other people.
http://en.wikipedia.org/wiki/Folie_%C3%A0_deuxWe're seeing that at work in this administration and among their supporters, all of whom are isolated from the rest of us in one way or another. The administration is in a bubble. Our delusional acquaintances restrict their viewing to Pox News and their reading to right wing web sites that confirm the delusion. They never stray outside them and find it exquisitely painful to have to interact with us.
The more they isolate themselves, the nuttier they are likely to get.