Spoken Language Abilities in Adults with High-Functioning Autism

Background: Most comprehensive studies of language abilities in high-functioning individuals with autism (HFA) have been focused on early development through adolescence, and very few on the adult high-functioning population. As a result, the pattern of abilities and disabilities of this group is not as well characterized.

Objectives: To obtain a comprehensive spoken language profile of adult HFA using a standardized language assessment with good validity and reliability, CASL 

Methods: Five HFA (diagnosis of autism confirmed by ADI-R and ADOS, ages 19-40) were administered the complete CASL and the results were scored according to the manual. In order to provide a common frame of reference for comparing core, index, and standard scores for our participants who are older than the normative age limit set for CASL (21;11), individuals aged 22 or older at the time of assessment were normed to age group 21;11. Cognitive function data were also collected using tasks such as Block Design (BD) and Rey Complex Figure Test (RCFT) to measured weak central coherence, which is a core deficit in autistic individuals across many domains. 

Results: Analysis of CASL’s category index scores revealed the lexical/semantic index score to be consistently the highest index score compared to other areas of language (syntactic, supralinguistic, and pragmatic). There is a significant difference between lexical/semantic and supralinguistic, which measures higher-level language processing. Within the supralinguistic subtests, the most consistent deficit in our HFA participants was the ability to explain non-literal language (subtest: Non-literal Language).  The abilities to derive meaning from context (subtest: Meaning from Context) and from prior knowledge (subtest: Inference), and to provide two different interpretations of an ambiguous sentence (subtest: Ambiguous Sentences) also tended to be below normal range. The participants exhibited a weakness in BD and a severe impairment in the copy portion of the RCFT, characterized by a preference for using a local rather than global strategy.

Conclusions: 1) Preliminary data suggest that CASL is a sensitive battery for capturing the typical language strengths and deficits in HFA even beyond its normative age range.  2) The overall language profile seen in these participants thus far is consistent with the literature on HFA in that lexical/semantic was an area of strength, syntactic ability was relatively intact, and deficits were shown in higher-level language processing and pragmatics. Difficulties observed on CASL subtests (Meaning from Context and Inference) are consistent with weak central coherence theory, which is also supported by participants’ performance on the RCFT. Further analysis and testing is needed to examine in detail the relationship between cognitive function and language processing tasks, to explain individual differences in performance in adult HFA.