Weaving Causal Explanations of Schizophrenia in Urban Areas

Abstract

Schizophrenia has long been reported to be more common in urban areas,1,2 although recent research suggests this association may not occur in low- and middle-income countries.3 Explanations of this urbanicity association, entwined with links between the disorder and socioeconomic deprivation, have led people to question the possibilities of a reverse causal association: do people with early illness or strong liability drift into cities and down the social scale, or do those environments exert a toxic effect? Few studies dissect city life from a socioenvironmental context,4 but urbanicity certainly is associated with cognition and the brain.5 Evidence is also emerging that part of the liability to living in deprived neighborhoods is associated with genetics; it is heritable, and, moreover, genes conferring liability to schizophrenia may be particularly involved.6