Clinical heterogeneity of schizophrenia.

The heterogeneity of schizophrenia has led to a multitude of diagnostic criteria systems. Thus, the best strategy for schizophrenia research might be the use of several diagnostic systems simultaneously. This polydiagnostic approach can be associated with isolating subtypes of symptoms or patients. In this way, the authors present several approaches such as, first, dimensional approaches, second, cluster analyses, and third the selection of a very homogeneous subtype with standardized criteria. One homogeneous subtype can be represented by deficit schizophrenia according to Carpenter as defined by the Schedule of Deficit Syndrome.