Objectives: The current study investigated the development of nonverbal communication skills (both JA and RB) from 12 to 18 months and links with autism symptom severity in infants at high- and low-risk for ASD. We hypothesized that children who experienced slower (i.e., less improved) development in these areas in the second year would present more severe symptomatology of ASD at 36 months. This developmental relationship would have implications for early detection of ASD as well as the focus and timing of early intervention.
Methods: Infant siblings of children with autistic disorder (n=111) and infants with no familial history of ASD (n=43) were assessed at 12, 18, and 36 months of age. JA (initiations and responses) and RB were assessed using the Early Social Communication Scales (Seibert, Hogan, & Mundy, 1982). A symptom severity algorithm (Gotham et al., 2009) was applied to the Autism Diagnostic Observation Schedule at 36 months (Lord et al., 2000). Hypotheses were initially tested using bivariate Pearson correlations. Where significant relations were observed, regression models were run to evaluate baseline language skills as a covariate and as a potential mediator between nonverbal communication skills and ASD severity.
Results: Baseline measures of responsive JA (RJA) and changes in RJA from 12-18 months predicted ASD severity at 36 months (p’s < .01), even when baseline language skills were controlled. Infant-initiated JA (IJA, pointing and showing, p = .01) at 12 months, but not change in IJA, predicted ASD severity. RB (pointing) at 12 months and change in these requesting behaviors predicted ASD severity (p’s ≤ .01), controlling for baseline language skills.
Conclusions: While previous research indicates that early nonverbal communication skills and rates of development affect later social skills secondary to ASD, our findings demonstrate an association between change in nonverbal communication skills (JA and RB) and subsequent ASD symptom severity. Research of this kind accentuates the importance of monitoring and treating early social communication skills in order to improve developmental outcomes in infants at risk for ASD.
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