Letter to the EditorLate-onset folie à deux in monozygotic twins
Introduction
Less than 500 cases of folie à deux have been reported worldwide making it a relatively rare psychiatric disorder (Lazarus, 1986). Lasègue and Falret initially defined the syndrome as a psychiatric disturbance that could be transferred from one individual to another under the following circumstances: if the individual that first exhibited the delusions (the “inducer”) was more intelligent and dominant than the secondary individual (the “induced”), if both patients were closely associated in social isolation, and if the delusions were non-bizarre and referred to shared anxieties or experiences (Arnone et al., 2006). The accepted treatment for this condition was separation of the inducer and the induced (Lazarus, 1986). In the DSM-5, shared psychotic disorder is noted as a sub-category in the section on other specified schizophrenic spectrum and other psychotic disorders rather than as a separate diagnostic entity in itself (Parker, 2014).
Folie à deux is most often seen in first-degree relatives, which supports the conjecture that genetic vulnerability is a necessity rather than simply an association. Even when folie à deux is seen in unrelated individuals there is significant family psychiatric history in affected individuals (Kendler et al., 1986, Lazarus, 1985). On the other hand, the recorded resolution of symptoms upon separation from the dominant individual proves that environmental factors have significant influence on the pathogenesis and course of the disease (Lazarus, 1985). Our case of folie à deux in monozygotic twins aims to provide additional insight into the dynamics between nature and nurture.
Section snippets
1. Case presentation
Ms. A is a 70 year-old woman with no formal psychiatric diagnosis and medical history significant for systemic lupus erythematosus complicated by lupus nephritis and uncontrolled hypertension. She was brought to the emergency department by ambulance with her twin sister for a sensation of asphyxiation due to thoughts of suspicious gaseous poisoning. She stated that around midnight a strong smell filled her sister's apartment and left a bitter taste in her mouth. She also heard loud coughing
1. Discussion
Here, we add another case to the literature with two unique features: monozygosity between affected individuals and late-onset of delusional symptoms. We hope this report will serve to further characterize the syndrome, aid diagnosis for future patients, and contribute to scholarly discussion regarding the interplay between environmental and genetic factors in psychotic disorders.
In 1956, Dewhurst and Todd proposed diagnostic criteria for folie à deux. The three criteria are as follows:
- 1.
The
Contributors
Authors Kalee Shah, Scott Breitinger, Jimmy Avari, and Dimitry Francois contributed to the literature search. Author Kalee Shah wrote the first draft of the manuscript. All authors contributed to and approved the final manuscript.
Conflict of interest
All authors declare that there are no actual or potential conflict of interest including any financial, personal or other relationships with other people or organizations within three (3) years of beginning this work that could inappropriately influence, or be perceived to influence, their work.
Acknowledgements
The authors do not have any acknowledgements.
References (11)
Folie a deux: psychosis by association or genetic determinism?
Compr. Psychiatry
(1985)- et al.
Induced psychotic disorder: clinical aspects, theoretical considerations, and some guidelines for treatment
Compr. Psychiatry
(1993) - et al.
Monozygotic twins, folie a deux and heritability: a case report and critical review
Med. Hypotheses
(1998) - et al.
The nosological significance of folie a deux: a review of the literature
Ann. General Psychiatry
(2006) - et al.
The psychosis of a association; folie a deux
J. Nerv. Ment. Dis.
(1956)