The positive/negative symptom distinction in schizophrenia. Validity and etiological relevance

This paper presents an overview of the literature on the positive/negative symptom distinction in schizophrenia, and explores the implications of the findings for etiological models. Despite the diversity in methodology and focus, certain consistencies emerge from the research. Most important are findings that negative symptoms show a stronger relation with premorbid dysfunction than positive symptoms, and are more predictive of concordance for schizophrenia in monozygotic twins. Thus it appears that negative symptom ratings partially tap some long-standing characteristics of the individual. Moreover, these characteristics appear to be influenced by genetic factors. The implications of the findings for models of the etiology of positive and negative symptoms are discussed.