Pragmatic Language Difficulties and Associations with Behavior Problems in Non-ASD Siblings of Children with ASD

Background:  In addition to being at heightened risk of developing ASD, siblings of children with ASD are at risk for other developmental concerns including structural language impairments (Drumm & Brian, 2013) and behavior difficulties (Schwichtenberg et al., 2013). However, pragmatic language has been underexplored in younger siblings of children with ASD. Low pragmatic competence has been linked to behavior problems (Ketelaars et al., 2010); whether such associations are amplified in very young children with a family history of ASD is unknown.

Objectives:  Aims included (1) evaluating pragmatic language outcomes (both severity and categorical classification) at 36-months in non-ASD siblings of children with ASD, and (2) examining concurrent associations between pragmatic language and behavior problems.

Methods:  Pragmatic language (measured by the Language Use Inventory, LUI) and behavior problems (using the Child Behavior Checklist, CBCL) were examined at 36-months in non-ASD siblings of children with ASD (high-risk, n=188) or typical development (low-risk, n=119). Risk group differences in pragmatic language were evaluated using ANCOVA (covariates: gender, structural language). Pragmatic impairment was defined as LUI scores <10^th percentile; group differences in rates of impairment were evaluated using chi-square. Multiple hierarchical regression was used to evaluate concurrent associations between LUI and CBCL scores controlling for risk group, gender, and structural language; moderation by risk group was examined.

Results: The high-risk group evidenced lower LUI scores than the low-risk group, F(1, 303) = 21.99, p < .001 and had higher rates of categorically-defined pragmatic language impairment (35% vs. 10%, respectively), χ² = 23.26, p < .001. For the 65 high-risk participants classified as pragmatically impaired, 54% had atypical CBE outcomes: n = 16 broader autism phenotype (BAP), 10 speech-language problem, 6 behavior problem, and 3 global developmental delay. Of the 12 low-risk participants identified as impaired pragmatically, 3 received atypical CBE outcomes (all BAP).

Regression analyses revealed that LUI scores were significantly negatively associated with externalizing and internalizing behavior (that is, better pragmatic language was associated with fewer behavior problems). Risk group moderated the association between LUI scores and externalizing behavior (p < .001) with examination of simple slopes indicating that the significant association was limited to the high-risk group. Risk group did not moderate the LUI-internalizing behavior association.

Conclusions:  Young children with a family history of ASD showed evidence of pragmatic language difficulties as early as 36-months, and pragmatic deficits were associated with externalizing and internalizing behavior problems. In the context of genetic risk for ASD, pragmatic language was associated with externalizing problems, but not in the absence of such risk. One possible mechanism underlying this stronger association in the high-risk group pertains to similar shared risk for both types of difficulties (Mulligan et al., 2009; Rommelse et al., 2011); indirect associations with shared risks may simultaneously put children with a family history of ASD at greater risk for both pragmatic language and externalizing problems. Follow-up of such samples will allow for clarification of likely bidirectional associations between pragmatic language and behavior problems. Close monitoring of pragmatic language development in this population may be warranted.