Similar to ASD, children with Specific Language Impairment (SLI) have difficulties in language learning. SLI refers to a developmental language disorder that is not associated with deafness, autism, or general developmental delay. Many previous reports have documented overlap in the behaviors and challenges shown by children with ASD and those with SLI, making people wonder what features of language impairment, if any, are specific to autism. An important new study1 was published in 2009 investigating language development in children with ASD and SLI, which showed that the loss of language skills is highly specific to children with ASD.
The study published in the Journal of Child Psychology and Psychiatry included 368 children with ASD and SLI from the United Kingdom. Parents were interviewed using the Autism Diagnostic Interview – Revised, which provided a detailed developmental history of the child and included information on loss of language skills (i.e. the milestone of acquiring either single words or short phrases was reached but then language development plateaued or was lost). The authors found that whereas 15% of children with ASD showed loss of language, only 1% of children with SLI showed similar patterns of loss. Curiously, they found that those children with ASD who later lost language skills acquired either single words or short phrases significantly earlier than those children with ASD who showed no signs of language loss.
The study reveals a surprisingly strong specificity for language regression and ASD, perhaps indicating that even though language impairment is common to both ASD and SLI, they may involve different biological mechanisms. Most importantly, the findings also have immediate clinical implications, suggesting that the presence or absence of language regression can be useful information in the differential diagnosis of ASD versus SLI for children presenting with language difficulties.