Laterality and mental disorders in the postgenomic age – A closer look at schizophrenia and language lateralization

Research Area: Research Year: 2015
Type of Publication: Article Keywords: Schizophrenia; Language lateralization; Dichotic listening; Genetics; Auditory hallucinations
Authors: Ocklenburg, Sebastian; Güntürkün, Onur; Hugdahl, Kenneth; Hirnstein, Marco
Most people are right-handed and show left-hemispheric language lateralization, but a minority exhibits left-handedness and right-hemispheric language lateralization. This atypical laterality pattern is observed significantly more often in schizophrenia patients than in the general population, which led several authors to conclude that there is a genetic link between laterality and schizophrenia. It has even been suggested that a failure in the lateralization process, orchestrated by genes, could be the primary cause of schizophrenia. However, the molecular genetic evidence for a link between laterality and schizophrenia is weak. Recent genetic evidence indicates that schizophrenia is not a single disorder but a group of heritable disorders caused by different genotypic networks leading to distinct clinical symptoms. To uncover the link between schizophrenia and laterality we therefore suggest a paradigm shift where genetics are not mapped on schizophrenia as a whole but on discrete schizophrenia symptoms. In addition, we provide a critical evaluation of current theories on the genetic link between schizophrenia and brain asymmetry.
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