Schizophrenic and Affective Psychosis: Twin and Family Studies

Abstract

The relative role of genetic and environmental factors in the etiology of schizophrenia is not entirely known. This review will cover research efforts directed toward clarifying an issue. Kraepelin’s early classification of the psychoses in 1899 according to descriptive and prognostic terms was into two major groups of psychoses: dementia praecox, dementing and irrecoverable insanity and the manic-depressive psychosis, a periodic recoverable psychosis (1). With this classification system efforts could begin toward determining etiologic factors. Bleuler conceived of a group of psychoses of no known organic origin which in 1911 he labeled as schizophrenia. In this group he placed dementia praecox, but also a group of recoverable psychoses, all of which shared a common set of primary symptoms including disturbance of association, affect and volition, and a varied number of secondary symptoms such as delusions and hallucinations.