Objective: To present a case report of folie simultanée in monozygotic twins. The literature describing folie à deux in twins is also reviewed and the common clinical findings are presented.
Method: Case presentation and review of the literature.
Results: Clinical observations of monozygotic twins with folie simultanée suggest that the delusions tend to progress over time with each twin reinforcing the delusion in the second.
Conclusions: The concept of a delusion resonating between individuals may account for the rapid progression and escalation of these delusions.