The continuum of linguistic dysfunction from pervasive developmental disorders to dyslexia.

This article examines speech and language impairment in relation to several common childhood psychiatric disorders. Similarities among disorders can be found in the associated language impairments, family histories, and certain language outcomes. The article describes prevalence surveys of speech and language disorders and the correlates of language impairment, such as IQ, socioeconomic status, and birth order. The association between language impairment and childhood psychiatric disorders (i.e., hyperactivity, autism) is investigated, and the outcomes of language impairment are discussed. Finally, the hypothesis that a common underlying neurolinguistic diathesis may be present for certain subgroups of psychiatrically disordered children is presented. In some groups, psychiatric disorder (i.e., hyperactivity) and linguistic impairment may develop in parallel as a function of an underlying neurodevelopmental immaturity. The relation between the linguistic impairment and neurodevelopmental immaturity requires clarification so as to disentangle their specific associations with the various disorders discussed.