Development of Nonverbal Communication Predicts Symptom Severity in Infants At Risk for ASD

Background: Nonverbal communication skills—including joint attention (JA) and requesting behaviors (RB)—are an essential component of early social interaction, intersubjectivity, and verbal communication. Impairments in these skills are among the earliest behavioral markers of Autism Spectrum Disorder (ASD) (Rozga et al., 2011).  Atypical trajectories of joint attention skills have been reported for children diagnosed with ASD by 24 months relative to typically developing (TD) children and children displaying features of the broader autism phenotype (BAP).  At 14 months, levels of initiating joint attention (IJA) differentiated infants diagnosed with ASD at the same age from those later diagnosed at 24 months (Landa, Holman, & Garrett-Mayer, 2007). These early social skills are related to social and behavioral symptoms secondary to ASD (Hutman et al., 2011), but the relation between JA development during the second year and primary symptom severity of ASD has not been evaluated.

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.