Continuum Versus Dichotomy in Theories of Schizophrenia*

There is a sharp difference of opinion in the psychiatric literature over whether schizophrenic disorders exist on a continuum with other mental disorders and normality, but this issue has in the past been overshadowed by another controversy—the role of genetic vs. environmental factors in the etiology of schizophrenia. This paper argues that the division of theories of schizophrenia into those emphasizing genetic and those emphasizing environmental factors overlooks similarities between certain genetic and certain environmental models. Arranging the theories of schizophrenia according to the concept of a continuum of disorder allows for a new perspective, by which monogenic theorists (e.g., Book 1953, Heston 1970, Kallmann 1946, and Slater and Cowie 1971) and certain environmental theorists (e.g., Alanen 1966 and Lidz 1973) form one group; while proponents of polygenic models (Gottesman and Shields 1973) and other environmental theorists (e.g., Bateson et al. 1956 and M. Bleuler 1965 and 1972) form a second group. The concept of a continuum of schizophrenic disorders is interpreted in various ways. At times, it is used in the context of phenomenology. This type of continuum refers to the lack of symptom specificity in schizophrenia—a lack that has been cited by Kraepelin (1971), Meyer (1948), Sullivan (1974), M. Bleuler (1965), and more recently Strauss and Carpenter