Biological, psychological and historical differences in a series of monozygotic twins discordant for schizophrenia

The subject of this meeting is transmission and schizophrenia, a behavioral syndrome which is a disease process in that there is a demonstrable breakdown of normal function, comfort and effectiveness in a given individual.

Abstract

THERE is an old Chinese proverb that says: “The beginning of wisdom is to call things by their right names.” To begin with, let us try to make sure that we are using the “right” words, and at a minimum, mutually understood words, by briefly defining our thoughts concerning the two phenomena which together constitute the subject of this meeting: transmission and schizophrenia. When we use the term schizophrenia, we mean a behavioral syndrome which (a) is a disease process in that there is a demonstrable breakdown of normal function, comfort and effectiveness in a given individual; (b) has a set of common denominator symptoms (thought, affect, and action disorder, delusions, hallucinations and other psychotic manifestations) such that the “typical”, hardcore patient presents no diagnostic difficulty to psychiatric workers of many different points of view and nationalities; and (c) a behavioral syndrome which has very unclear limits, so that as one moves away from the hardcore cases there is an increasing degree of difficulty in arriving at diagnostic consensus. In regard to the other major concept with which we are concerned, i.e. transmission, Webster tells us that transmission is the act, operation or process of sending or transferring from one person to another; or passing on or down to others. Some question may be raised concerning how germane this concept is, at the present stage of our knowledge of schizophrenia. However, if we consider the various models that are implied by the concept of transmission of illness, its usefulness becomes clear. Illness can be transferred from one individual to another by means of the transfer of an active pathogen, as in bacteria1 infection; or by genetic transmission as in phenylketonuria. There is also a type of social transmission in the sense that children of poverty stricken, socially backward, slum dwellers have a much greater likelihood of coming down with tuberculosis, for example, not necessarily because their parents have transmitted to them a particular bacillus or a given genetic predisposition, but because they have been given a particular social heritage and have been reared in a particular environment which influences the susceptibility to the bacillus which is the prime source of the illness. Another model we need keep in mind demonstrates the fact that though children may very predictably show the behavior of their parents, this need not have any genetic component, as exemplified by the fact that children of French-speaking parents speak French, of English-speaking parents speak English, and so forth.