Shared Psychotic Disorder in Monozygotic Twins: A Case of Schizophrenia

Background: Shared psychotic disorder, also known as folie à deux, is a rare condition in which two individuals, often emotionally close family members, share common delusions. This disorder typically involves one individual transmitting their delusion to another. It is particularly interesting when observed in monozygotic twins, who share an identical genetic background and often have emotionally fusion-like relationships. Case Presentation: This article presents a clinical case of folie à deux in homozygous twins, both diagnosed with schizophrenia. Patient A developed an initial psychotic breakdown with persecutory and megalomaniac delusions. Patient B, after a brief period of observing her sister’s delusions, developed a similar delusional syndrome. Both patients were treated with atypical neuroleptics, and Patient B showed significant improvement after separation, while Patient A's symptoms persisted. Discussion: This case highlights the role of genetic predisposition and emotional bonds in the development of shared psychotic disorder. It is suggested that genetic factors, especially in monozygotic twins, play a crucial role in the shared psychotic disorder, while relational dynamics and emotional attachment, such as the fusion-like relationship between the twins, can facilitate the transmission of delusions. The case also compares the observed symptoms to other similar cases in the literature, reinforcing the simultaneous folie theory. Conclusion: The case demonstrates the importance of therapeutic separation and pharmacotherapy in managing shared psychotic disorder. The improvement in Patient B after separation, combined with the appropriate use of atypical antipsychotics, suggests that a combination of treatment approaches is necessary for the successful management of folie à deux in genetically predisposed individuals.