A Danish Twin Study of Schizophrenia

Abstract

Previous studies on schizophrenia in twins have quite recently been reviewed in detail by Gottesman and Shields (1966a) and Shields (1968). The indications of concordance in different series are highly diverging, in monozygotic pairs ranging from near unity to zero. The high concordance rates found by Luxenburger (1928), Kallmann (1946) and Slater (1953) stress the importance of genetic factors in the aetiology of schizophrenia, whereas the low concordance rate in two recent Scandinavian twin series (Tienari, 1963; Kringlen, 1966) has given rise to the question whether special genetic or environmental factors prevail in some populations. It has, therefore, been found of interest to study schizophrenia in a Danish twin population.