Elsevier

Comprehensive Psychiatry

Volume 45, Issue 2, March–April 2004, Pages 155-160
Comprehensive Psychiatry

Folie a deux versus genetically driven delusional disorder: case reports and nosological considerations

https://doi.org/10.1016/j.comppsych.2003.09.004Get rights and content

Abstract

Folie a deux is thought to occur in persons who live close together, so that delusions of the primarily ill patient are adopted by the partner. Alternatively, if both patients are related, they may share the same genetically driven psychiatric illness. We present the cases of two psychotic couples (monozygotic twins and a mother and daughter pair, respectively), in which both subjects featured an almost identical psychopathological syndrome with the same delusional content and thus fulfilled the diagnostic criteria of folie a deux. When Leonhard’s diagnostic system was applied, all four patients were found to suffer from affect-laden paraphrenia, arguing against the presence of folie a deux in those dyads. Thus, thorough psychopathological examination in suspected folie a deux settings can help to obtain valid diagnoses.

Section snippets

Case 1: B.N. and C.N

B.N. and C.N. were born 1958 as monozygotic twins as evidenced by molecular genetics. Their mother had no psychotic illness. The father died in the 1970s due to alcohol intoxication. He was reported to be extremely suspicious and paranoid, and seemed to suffer from acoustic hallucinations. Based on the available information, a working diagnosis of paranoid schizophrenia can be assumed. The twins’ brother is mentally healthy.

Both twins completed high school without problems. During their early

Discussion

FD is a rare psychiatric condition that might cause diagnostic problems, especially if the partners are consanguineous19, 20: does the supposed secondary patient suffer indeed from a “transmitted” delusional belief or from an independent, endogenous psychosis? In the case of unrelated patients, a genetic connection can be ruled out; we will thus focus on related subjects. Two exemplary cases of psychotic couples have been presented, in which both participants shared similar psychopathology and

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