Positive or negative symptoms--which are more appropriate as diagnostic criteria for schizophrenia?

For over a decade there has been a consensus that the diagnosis of schizophrenia should rest upon the presence of positive symptoms. Recently it has been suggested to give negative symptoms, which have played a prominent role in research, more diagnostic importance again. This study investigated the usefulness of that suggestion. In a sample of 489 inpatients covering the whole range of psychiatric diagnoses, the frequencies and prevalences of positive and negative symptoms were determined. Analyses of variance were calculated to assess the diagnostic validity of the different classes of symptoms. The study demonstrates that positive symptoms are of much higher diagnostic value than negative symptoms. A change of diagnostic procedures giving more importance to negative symptoms is discouraged.