Differences Between Receptive and Expressive Language Abilities In Low Functioning Children with ASD

Background: Receptive and expressive language are often studied separately in ASD, except for some studies in toddlers (e.g. Weismer et al., 2010). Prior research indicated several predictors of early language abilities. Both limited intentionality and symbol formation are considered to be core deficits in the communication development of individuals with ASD (Travis & Sigman, 2001). Several studies identified joint attention as a predictor for language development in ASD (e.g. Dawson et al., 2004), but the role of symbol understanding still remains unclear.

Objectives: 1) to explore differences in receptive and expressive language abilities of low functioning children with autistic disorder compared to children with an intellectual disability and typically developing children; 2) to examine whether and how precursors of language (joint attention and symbol understanding) are related to concurrent receptive and expressive language abilities in these groups.

Methods: In this study, 36 children with autistic disorder and intellectual disability (AD+ID) (confirmed by the ADOS and the DISCO-11) are compared with 26 children with intellectual disability (ID) and 34 typically developing children (TD) with regard to their language abilities. Groups were comparable with respect to non-verbal mental age (NVMA range: 2 to 5 years). Language abilities were assessed using the Reynell test for Dutch language comprehension, the Schlichting test for Dutch language production, and the Dutch Communicative Development Inventories. Joint attention was based on items from the ADOS and symbolic understanding of pictures was measured with a doll house experiment.

Results: Repeated measure ANCOVA, with NVMA as covariate, revealed significant differences between the groups: the AD+ID group obtained lowers scores than the ID-group, and the TD group outperformed the ID group. The language profiles differed significantly among the three groups. The AD+ID group obtained higher scores on expressive than on receptive language, whereas the ID and the TD groups showed the opposite profile. For the AD+ID group, hierarchical regression analyses indicated that symbol understanding and joint attention were most strongly related to language abilities. Symbol understanding was a stronger predictor for receptive language than joint attention. In the ID-group, NVMA and symbol understanding were significant predictors for receptive language, whereas the final model for expressive language only consisted of NVMA. NVMA was also a significant predictor for both receptive and expressive language abilities in TD children. 

Conclusions: In contrast with the two control groups, receptive language abilities are significantly weaker than expressive language abilities in children with AD and ID. Consequently, language comprehension in low functioning children with AD may be overestimated. Next to joint attention, symbol understanding contributes to receptive and expressive language abilities in low functioning children with AD. Therefore, symbol understanding should be an important focus in assessment and treatment with respect to communication problems in ASD.