Positive and negative symptoms of schizophrenia. Their course and relationship over time

Recent approaches to subtyping schizophrenia have made use of the concepts of positive and negative symptoms. It is sometimes assumed that positive and negative symptoms are distributed discontinuously or inversely. Many of the studies that have examined this concept are cross-sectional. This research examines the relationships among positive and negative symptoms in a sample of 41 DSM III diagnosed schizophrenics. Using the SANS and the SAPS, symptoms are assessed, first, in the acute phase of the illness and then, 6 months later, in a period of relative remission. Results showed that positive and negative symptoms were not inversely related at either phase of the illness. Secondly, in comparison to positive symptoms, negative symptoms were highly intercorrelated at both times. Thirdly, the presence of negative symptoms in the acute phase was highly predictive of the presence of negative symptoms at follow-up. Implications for the longitudinal course of symptoms in schizophrenia are discussed.