A case against subtyping in schizophrenia.

In this paper we consider the generally accepted view that schizophrenia is 'heterogeneous'. We point out that the view derives from prima facie evidence from clinical presentation, studies of course, and factor analysis. However, upon closer examination internal contradictions are apparent, e.g., subtypes change, different groupings of symptoms cooccur in the same individual. Another type of paradigm, depending on careful study of case controls (e.g., monozygotic twins discordant for schizophrenia) and distributions, indicates that abnormalities in neurocognition, regional cerebral blood flow, and regional neuroanatomy may be present in nearly every patient, irrespective of absolute level or diagnostic subtype. These results suggest that a simple model in which patients vary along a severity dimension might parsimoniously explain much of the variance. Thus, while it is possible and even probable that schizophrenia may have many etiologies, phenocopies may represent the expression of a unitary pathogenesis of greater or lesser impact.