Folie à deux is a shared psychotic disorder where the delusion is shared between two individuals.
Criteria for a folie à deux as described by Dewhurst and Todd:
- definite evidence that the partners had been in intimate association
- a high degree of commonality in the content of delusion, although the formal psychosis may differ
- unequivocal evidence that the partners share support, and accept each other’s delusions
In the DSM -5 it is included under the section on psychotic disorders and does not exist as a separate entity.