The Prevalence of Autistic Spectrum Disorders in Adolescents with a History of Specific Language Impairment (SLI)

Background: Traditionally, autism and specific language impairment (SLI) have been regarded as distinct disorders but, more recently, evidence has been put forward for a closer link between them: a common set of language problems, in particular receptive language difficulties and the existence of intermediate cases including pragmatic language impairment. The present study aimed to examine the prevalence of autism spectrum disorders in a large sample of adolescents with a history of SLI. Method: The presence of autism spectrum disorders was examined in seventy-six 14-year-olds with a confirmed history of SLI. A variety of instruments were employed, including the Autism Diagnostic Interview-Revised (ADI-R), the Autism Diagnostic Observation Schedule (ADOS) and the Family History Interview (FHI). Results: The prevalence of autism spectrum disorders in young people with SLI was found to be 3.9%, about 10 times what would be expected from the general population. In addition, a much larger number of young people with a history of SLI showed only some autism spectrum symptoms or showed them in a mild form. Conclusions: Young people with SLI have an increased risk of autism. The magnitude of this risk is considerable. In addition, a larger proportion (a quarter of individuals) present with a number of behaviours consistent with autism spectrum disorders.