Shared psychotic disorder in children and adolescents: la folie à deux

The interplay between genetic vulnerability and the impact of living with an adult suffering from a psychotic disorder seems to be central to shared psychotic disorder.

The description of the common psychotic disorder

Advertising Psychotic disorders mainly include symptoms such as delusions, hallucinations, disorganized thinking and language indicating loss of contact with reality (APA, 2013). The common psychotic disorder (DPC), o foil to two, was first described in 1877 and consists in the transfer of delusions and / or abnormal behavior from a “primary” (inducing) case to one or more “secondary” (induced) cases. It usually occurs in a person or group of people (often in the family) who is related to a person with delusions or schizophrenia (Vigo et al., 2019).

The incidence of the disorder is low, between 1.7 and 2.6% (WHO, 1992). However, many cases are likely to be underreported and therefore underdiagnosed, which is why its true prevalence is still difficult to estimate.

In the literature, there are several cases of foil to two in the family, especially of shared delirium between parents and children (Ilzarbe et al., 2015). Children and young people are often involved in shared psychotic disorderadopt the delusions of their caregivers to ensure peaceful coexistence among all family members (Vigo et al., 2019).

The psychotic disorder is divided between environment and genetics

The genetic and environmental contributions of this disorder are still unclear. The initial studies focused more on the relationships established by the people involved. Some risk factors may be: the presence of a dominant family member, dependent and ambivalent family relationships, frequent family crises, domestic violence, violent behavior, and social isolation (Gralnick, 1942; Tseng, 1969). Other studies have focused on the psychiatric history and comorbidities of the individuals involved. Many have pointed to a high incidence of schizophrenia in this population and a high presence of psychiatric comorbidities in the induced subjects, and concluded that a genetic predisposition to schizophrenia or psychotic disorders was necessary in the development of shared psychosis (e.g., Scharfetter, 1970; Silveira & Seeman, 1995). Thus, psychosocial circumstances could represent a trigger for a transient psychotic episode in a vulnerable patient at high risk for psychosis.

To better understand the still unclear aspects related to this pathology in children and adolescents, a systematic review of Vigo and colleagues (2019) focused on the condition of foil to two in families with children under the age of 18, taking into account the associated family genetic risk and environmental risk factors. The results showed that in most families with children and adolescents involved in foil to two there was a high incidence of social isolation, which could potentially strengthen the pathological relationship between the persons involved. Furthermore, many of these adolescents have no contact with a healthy adult within the family, which was previously reported by Rutter and colleagues (1974) as a protective factor. Although social isolation in these families has been extensively described in the literature (e.g., Berner et al., 1986), it is still unclear whether it represents a cause or a consequence of the condition. One possible explanation could be that families who have developed psychotic symptoms may be more suspicious, as a predisposing trait, and therefore less likely to establish external relationships.

In terms of the genetic contribution, the inducers had higher incidence of psychiatric history than the induced ones, with a widespread diagnosis of schizophrenia (a disorder showing a high heritability), but no difference in the family’s psychiatric history; it should be borne in mind that inducers are often first-degree relatives of inducers who, in most cases, have been given a definitive diagnosis of schizophrenic spectrum disorder.

Advertising In light of what has been reported, two key questions still arise: Would the induced have developed psychotic symptoms even without intimate contact with the inducers? And again young with shared psychotic disorder should they be considered at high risk of developing schizophrenia in the future? It is important that studies of adolescents with a high genetic risk of psychosis have reported a greater likelihood of developing psychosis than the general population (Myles – Worsley et al., 2007), but not all adolescents in these families (exposed to environmental stressors) and carriers). of genetic vulnerability) develop psychotic symptoms. The interplay between genetic vulnerability and the impact of living with an adult suffering from a psychotic disorder therefore appears to be central to foil to two. Distinguishing genetics from environmental effects in these cases can help prevent psychosis from developing in younger people at risk.

In contrast to previous literature, which showed that women were more often induced subjects (e.g. Silveira & Seeman, 1995), the results of this review showed that in the case of shared delirium involving children and adolescents, women seem to mostly to be induce. . This finding may be due to the observed tendency for single-parent families to be led by a woman (Silveira & Seeman, 1995) or the relative vulnerability of children and adolescents to their mothers.

Treatment of shared psychotic disorder

In conclusion, in terms of treatment, previous studies recommended physical separation as the preferred treatment (Mentjox et al., 1993). But in the review conducted by Layman and Cohen (1957), including 140 cases of foil to two, in only one case did the induced ones come spontaneously after separation, consistent with other recent reviews showing that separation from the primary case was inadequate treatment (Arnone et al., 2006). This finding is also supported by the review presented here, which does not show any statistical relationship between symptom remission and separation. When children or adolescents are involved, it is worth remembering that separation can even be traumatic (Drucker & Shapiro, 1982).

Mentjox and colleagues (1993) suggest that intervention should focus on psychological rather than physical separation, promoting independence between different members and taking into account the individual characteristics of the individuals involved. An approach with psychological interventions may be more suitable for children and adolescents who primarily manifest themselves with psychotic symptoms in connection with foil to two.

Recommended by the editors


  • Arnone, D., Patel, A., & Tan, GMY (2006). The nosological significance of Folie à Deux: a review of the literature. Annals of General Psychiatry, 5 (1), 1-8.
  • Berner, P., Gabriel, E., Kieffer, W., & Schanda, H. (1986). ‘Paranoid psychoses’. Psychopathology, 19 (1-2), 16-29.
  • Dewhurst, K., & Todd, J. (1956). Associations psychosis: Foil à deux. Journal of Nervous and Mental Disease.
  • Drucker, M., & Shapiro, S. (1982). Issues of separation related to psychosis in twins. Comprehensive Psychiatry, 23 (2), 136-142.
  • Gralnick, A. (1942). Foil à deux – associations psychosis; a review of 103 cases and the entire English literature, with case presentations. Psychiatric Quarterly.
  • Ilzarbe, D., Vigo, L., Ros-Cucurull, E., Baeza, I., & Sugranyes, G. (2015). A case of foil à trois induced by a child. Journal of Clinical Psychiatry, 76 (1), 2330.
  • Layman, WA, & Cohen, L. (1957). A modern concept of foil à deux. Journal of Nervous and Mental Disease.
  • Lasègue, EC, & Falret, J. (2016). The foil to two (or communal foil). Dialogues in Philosophy, Mental & Neuro Sciences, 9 (2).
  • Mentjox, R., van Houten, CA, & Kooiman, CG (1993). Induced psychotic disorder: clinical aspects, theoretical considerations and some guidelines for treatment. Comprehensive Psychiatry, 34 (2), 120-126.
  • Myles-Worsley, M., Blailes, F., Ord, LM, Weaver, S., Dever, G., & Faraone, SV (2007). Palau Early Psychosis Study: distribution of cases by level of genetic risk. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics, 144 (1), 5-9.
  • Rutter, M. (1974). Parent-child separation: psychological effects on children. Psychiatry of the Child.
  • Scharfetter, C. (1970). On the hereditary aspects of symbiotic psychoses: A contribution to the understanding of schizophrenia-like psychoses. Clinical Psychiatry.
  • Silveira, UM, & Seeman, M. (1995). Folie-à-deux or shared psychotic disorder (SPD): A critical review of the literature. Can J. Psychiatry, 40, 389-395.
  • Tseng, WS (1969). A paranoid family in Taiwan: A dynamic study of foil à famille. Archives of General Psychiatry, 21 (1), 55-63.
  • Vigo, L., Ilzarbe, D., Baeza, I., Banerjea, P., & Kyriakopoulos, M. (2019). Shared psychotic disorder in children and adolescents: a systematic review. European Child & Adolescent Psychiatry, 28 (12), 1555-1566.
  • World Health Organization. (1992). ICD-10 Classification of Mental and Behavioral Disorders: Clinical Descriptions and Diagnostic Guidelines. World Health Organization.
Condition © 2011-2022 All rights reserved.

Pictures (top to bottom) of:

Leave a Comment