Genetic or Psychogenic? A Case Study of “Folie à Quatre” Including Twins


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.

DOI: 10.1155/2015/983212

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@inproceedings{Ohnuma2015GeneticOP, title={Genetic or Psychogenic? A Case Study of “Folie {\`a} Quatre” Including Twins}, author={Tohru Ohnuma and Heii Arai}, booktitle={Case reports in psychiatry}, year={2015} }