The etiology of schizophrenia and the origin of language: Overview of a theory

Berlim, Marcelo T.; Mattevi, Betina S.; Belmonte-de-Abreu, Paulo; Crow, Timothy J.

doi:10.1053/comp.2003.50003

« Previous Next »Comprehensive Psychiatry
Volume 44, Issue 1 , Pages 7-14, January 2003

The etiology of schizophrenia and the origin of language: Overview of a theory

From the Schizophrenia Research Group, Department of Psychiatry and Forensic Medicine, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil; Department of Psychiatry, Warneford Hospital, Oxford University, Oxford, UK; and the Prince of Wales International Centre for Research on Schizophrenia and Depression (POWIC), Oxford, UK.

Abstract

Schizophrenia is present in all human populations with approximately the same incidence. Why does such illness persist given that it is associated with a reproductive disadvantage? What is the balancing advantage? A possible explanation is linked to human language. According to this hypothesis schizophrenia occurs as a manifestation of genetic diversity associated with language—the function by which Homo sapiens has separated from other primate species. Language originated by a genetic mutation that allowed the cerebral hemispheres to develop with a degree of specialization (or lateralization) reflected in cerebral asymmetries. Individuals with schizophrenia show lesser structural and functional brain asymmetries than the population as a whole, and this finding can be interpreted as a delay, or failure in, establishing hemispheric dominance for language. We review recent evidence supporting this theory.

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