Diglossia in the Etiology of Schizophrenia: A Hypothesis

A hypothesis offering diglossia as a potential risk factor for schizophrenia is presented. This is supported primarily by an account of the numerous co-occurrences between the diglossic phenomenon and the established risk factors and features of schizophrenia, such as language impairment, working memory dysfunction, social adversity, urbanicity, migration, and ethnicity, as well as some of the broader educational elements including illiteracy, reading deficits, and poor academic attainment. With an emphasis on the inherent role of language in schizophrenia and the demand for elucidating a mechanism behind its risk factors, we propose that a diglossic environment in childhood may constitute a neurodevelopmental insult predisposing to the development of the disorder. This relationship may be mediated by the reduced lateralization of language in the brain, which has been observed in relation to schizophrenia.