Simultaneous Occurrence of Psychotic Episodes in Monozygotic Twins

Abstract

This paper is a report of the simultaneous occurrence of psychotic episodes in a pair of 21-year-old monozygotic twin girls, with discussion of the psychodynamic factors involved. The occurrence of psychosis in twins is a striking phenomenon, the etiology of which has been debated by various schools of thought. Most authorities agree that the etiology involves genetic, dynamic, psychological, and cultural factors. Gedda¹ made an extensive survey on the subject of twins and reviewed the world literature prior to 1949. Gordon² described twins as being more closely related to each other than to their other siblings, with an undoubtedly greater physical and emotional affinity between them. The occurrence of psychosis in twins was formerly described as a special type of psychosis by some German authors under the term Zwillingirresein, and by some French authors as folie gémellaire. They emphasized the genetic factor in describing the simultaneous appearance of