Children with autism spectrum disorders (ASD), whose core symptoms include impairments in communication, social interaction, and repetitive, stereotyped behaviors, are typically distinguished from children with developmental language disorders (DLD). DLD itself cannot be diagnosed in a child with ASD (DSM-IV-TR). Yet, there are areas of overlap between these two disorders that pose challenges for differential diagnosis. One area of overlap has been in language impairment, which can influence a child’s communicative competence and social-emotional behaviors.
There have been varying reports over the years in the types of language issues, degree of severity, and percentage of children with ASD who show language impairments. High functioning verbal children with autism have been reported to have no specific deficits in phonology, syntax, or lexical knowledge; deficits mainly in pragmatics; and, then again, in as many as 50% of such an ASD group, significant difficulties in structural language and a pattern of impairments that resembles DLD (Kjelgaard and Tager-Flusberg, 2001).
Objective is to document incidence of language impairment in a well-characterized group of high functioning verbal children with ASD and to compare their language issues with those of an equally well-characterized group of children with DLD.
Children, ages 4-8, were given a comprehensive battery of language and neurocognitive measures. Language measures included the CELF-Preschool 2/CELF-4, Nonword Repetition, PPVT-III, NEPSY Narrative, Verbal Fluency. Spontaneous language analyses were also obtained.
Classification into the ASD group (N=29) utilized the Social Communication Questionnaire (SCQ); the revised algorithm of the ADOS; and DSM-IV-TR-based clinical diagnosis of ASD made via independent ratings and consensus agreement by a team of licensed psychologists and speech language pathologists. Classification into the DLD group (N=19), following an equally rigorous process, utilized Tomblin’s Epi-SLI criteria (Tomblin et al., 1997) or a CELF index score at -1 s.d. plus a spontaneous language measure at -1 s.d.; and DSM-IV-TR-based consensus clinical diagnosis. ADOS scores were not used to make or rule out a diagnosis of DLD; clinical diagnosis did rule out ASD in every child with DLD.
The DLD and ASD groups were well matched on nonverbal IQ (104 and 109, respectively) and age (6; 3 and 6; 5), p>0.50 in both cases.
Results: In the ASD group, 50% met the EpiSLI criteria, 65% the CELF + Spontaneous Language criteria, and 69% either criteria. In the DLD group, these percentages were 77%, 94%, and 100%. Across the 3 Epi-SLI sub-domains (vocabulary, grammar, and narrative) and 2 modalities (receptive and expressive), the shapes (but not the elevations) of the profiles of the two groups were similar (e.g., more issues in expressive language than receptive; more issues in grammar and narrative than in vocabulary).
These findings support research that demarcates the high percentage of high-functioning, verbal children with ASD who have language impairments. It also contributes to our understanding of the overlap between ASD and DLD in patterns of language impairment. It beckons for further disclosure areas of essential difference between these two disorders, especially in the area of language and communication.