Pragmatic Language Characteristics of Adolescents with Autism and Their Siblings

Background:  Pragmatic language impairment is a core feature of autism spectrum disorder (ASD), even in individuals with normal structural language and intelligence. Subtler pragmatic language differences have been observed in parents of children with ASD, suggesting that this domain is part of the Broad Autism Phenotype (BAP). However, few studies have measured pragmatic language in unaffected siblings of children with ASD, nor have they investigated correlations in pragmatic language abilities between probands (i.e., individuals with ASD) and their siblings. 

Objectives:  To compare pragmatic language behaviors in probands, their siblings, and typically-developing control subjects during semi-naturalistic conversational interactions. 

Methods:  To date, 41 high-functioning probands (M = 13.40 years, SD = 3.65), 26 siblings (M = 13.09 years, SD = 3.02) and 3 control subjects (M = 15.39 years, SD = 1.46) have been included in this study (with additional control testing currently underway). The Pragmatic Rating Scale for School-Age Children (Landa, 2011) was used to code videos of the Autism Diagnostic Observation Schedule (Lord, 2000). This 33-item measure assesses pragmatic language abilities and associated social-communicative characteristics (e.g., suprasegmental characteristics, nonverbal behaviors). Item scores range from 0 (normal) to 2 (atypical), with higher scores indicating poorer pragmatic abilities. Six subscale scores and a total score are calculated by summing item scores. 

Results:  Groups differed significantly on the total score (F(2, 67) = 23.27, p < .001) and all subscales (Fs > 7.51, ps < .01) except for diversity of speech acts (p > .05). Post-hoc comparisons indicated that the ASD group demonstrated poorer pragmatic abilities than the sibling group on presupposition, discourse management, speech and language behaviors, and nonverbal communication, and they differed from both siblings and controls on suprasegmental speech characteristics and the total score. Siblings scored higher than controls on four subscales and the total score (mean difference range: 0.21 – 2.60), but no significant group differences were observed. It is suspected that the differences between the control group and the ASD and sibling groups did not reach significance because of the low number controls subjects. Several correlations emerged between probands and their siblings. Siblings’ scores on the presupposition subscale were correlated with probands’ discourse management scores (r = .50, p < .05), and were marginally correlated with proband total score (r = .43, p < .10). Suprasegmental speech characteristics in siblings were correlated with probands’ scores on the discourse management and suprasegmental subscales (rs > .52, ps < .05), and the probands’ total score (r = .49, p < .05). Siblings’ total score was also marginally correlated with probands’ discourse management abilities (r = .42, p < .10). Interestingly, when proband scores were examined in relationship to those of an unrelated child from the sibling group, matched on age and gender to their own sibling, no significant correlations emerged, supporting familial relationships in pragmatic language ability. 

Conclusions:  These results provide additional evidence of pervasive pragmatic language impairments in high-functioning adolescents with ASD, and also support the possibility that pragmatic language characteristics stem from shared genetic and/or environmental factors.