Folie à deux in Japan — analysis of 97 cases in the Japanese literature

Abstract

In order to clarify the characteristics of folie à deux in Japan, we examined a total of 97 cases of folie à deux in the Japanese literature covering a period of 90 years, and compared them with the cases reported in Western countries. About 75% of the Japanese cases occur in two individuals, and of these are family cases. The most common combinations are mother-child and married couple. Mother-child combinations are much more common than father-child combinations. Female subjects are more often involved than males. The most common diagnosis for the dominant partner is schizophrenia, and the most common diagnosis for the submissive partner is paranoid reaction. Delusion is the most common symptom shared by both partners in Japan. Comparing these Japanese cases to Western ones, sister-sister combinations are less frequent, younger subjects influence the older ones more, and acute religious delusion is more common in Japan than in Western countries.

A rare case of shared mania: An unusual entity

“…In folie a deux, delusions are usually persecutory [8] or grandiose, [9] although in our cases no delusion could be established either in primary or the secondary case. Usually, persons are closely associated for a long time and typically live together in relative social isolation.…”

Case Report of Shared Psychotic Disorder or ‘Folie a Deux’ in Two Geriatric Sisters

“…A review of 97 cases of shared psychotic disorder in Japan revealed the average age of dominant partner was 38 years old and average age of submissive partner was 36 years old. 4 Another review of 42 cases from 1993-2005 showed the mean age in primary patient was 52.7 and mean age in secondary patient was 45.9. 5 Nevertheless, shared psychotic disorder may present in any age group.…”

“…8 The disorder is more common in females than males for both primary and secondary patients. 4,5,9 Primary patients are typically observed to be more intelligent, older, and more aggressive/dominant whereas the secondary patients are generally younger, less intelligent, passive, and dependent. 3,10 Associated comorbidity in the primary patient Case Report of Shared Psychotic Disorder or 'Folie a Deux' in Two Geriatric Sisters …”

“…3 The primary patient is known as the "dominant" or "principle" partner and the secondary patient, who is influenced by the primary patient, is known as "submissive partner" or "associate." 4 The disorder is mainly presented within families, most commonly between husband and wife, as well as between two siblings. Average age of onset for disorder in both primary and secondary patient is in the adult age group, 4,5,6 however may affect any age of population.…”

“…4 The disorder is mainly presented within families, most commonly between husband and wife, as well as between two siblings. Average age of onset for disorder in both primary and secondary patient is in the adult age group, 4,5,6 however may affect any age of population. 7 Review of literature revealed only 17 cases of shared psychotic disorder in the geriatric population, ages 65 and older.…”