title: Genetic or Psychogenic? A Case Study of "Folie à Quatre" Including Twins.
abstract: Shared psychotic disorder, characterized by shared delusion among two or more subjects (termed "Folie à deux," "trois," etc.), is often associated with strong religious beliefs or social isolation, factors creating strong psychological sympathy. Recently, we treated a rare familial case of "Folie à quatre" in central Tokyo without such influences. The proband was a schizophrenia patient and younger brother within monozygotic twins. Positive symptoms were "transmitted" to remaining family members, his elder brother, mother, and father father, in a relatively short period of three months. Although the pathophysiology of these positive symptoms (delusions and hallucinations) remains unclear, the transmission pattern suggests the primacy of social and environmental factors (and/or their interaction), while genetics appeared less influential in this "Folie à famille." Although undiagnosed psychoses in the whole family cannot be excluded, they did not share the other negative schizophrenia symptoms of the proband. A strong familial connection appeared to be the most important factor for the common delusion and hallucination.
authors.affiliation: Juntendo University Schizophrenia Projects (JUSP), Department of Psychiatry, Faculty of Medicine, Juntendo University, Tokyo, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Ohnuma
authors.affiliation: Juntendo University Schizophrenia Projects (JUSP), Department of Psychiatry, Faculty of Medicine, Juntendo University, Tokyo, Japan.
authors.forename: Heii
authors.initials: H
authors.lastname: Arai