Concrete thought, expressed as concrete language, is a feature of psychotic illnesses. At present it is not known whether concrete language and thought precede the illness and are present at all points on the psychosis spectrum, from clinical disorder to psychotic experiences in the general populations. Previous work on ALSPAC data has investigated the association between parent report of child's language complexity and not found an association with later psychotic experiences. A collaborator from the Tokyo Teen Cohort has found an association between less complex written language in childhood and later psychotic experiences. It would be useful to investigate the same question in a language with a different structure from Japanese.