[Contribution of epidemiological research to the classification of mental disorders].

This is an attempt to have an overview of the problem of classification of mental disorders and of the various contributions offered by epidemiological research in the field. A brief introduction discusses the correct status of classification and its antecedents, supplemented by a glossary of terms used frequently in the field. A series of international studies bearing on the problem of definition of mental disorders in different cultures is presented and discussed as well as the matter of standards and comparison. The problems of validity, reliability and use of instruments are illustrated by the presentation of widely used instruments. A summary review of the rationale and principles for quantitative taxonomic methods is presented with special refference to numerical taxonomic and to the comparative evaluation of different methods of cluster-analysis. The subject of multiaxial classifications is presented through a brief description of currently used methods. Refference is also made to longitudinal studies both prospective and retrospective, and to their possible present and future value. Final comments are made about the present state of development and to the various obstacles which interfere with the task of finding a "common language" for classificación of mental disorders.