Beyond Pointing: Gesture Profiles in the First Year Differentiate Infants with ASD, Language Delays, and Typical Development

Background:  Given the high recurrence rates of autism spectrum disorder (ASD) among siblings (Ozonoff et al., 2011), it has become increasingly important to identify high-risk infants who have the greatest likelihood of developing ASD as early as possible. A deficit in pointing has been identified as an indicator of ASD in the second year (Baron-Cohen et al., 1996; Wetherby et al., 2004), but little is known about other specific gestures in infants with ASD.

Objectives:  To investigate the development of five gestures (showing, giving, protodeclarative pointing, waving, and raising arms to be picked up) at 9 and 12 months in infants at high and low risk for ASD and to examine whether proficiency in individual gestures can predict diagnostic classification at 24 months.

Methods:  Parents of 79 infants (48 high-risk, 31 low-risk) completed the MacArthur Communication Development Inventories for their infants at 9 and 12 months.   Infants were deemed proficient in specific gestures if parents reported that they used them ‘often.’  At 24 months, infants were classified as likely having ASD, exhibiting language or mild social-communication delays (LAN), or developing typically (high-risk TD and low-risk TD).

Results:  At 9 months, the only gesture that infants used frequently was raising arms to be picked up, but there were no between-group differences. At 12 months, the sole gesture that differentiated ASD infants from all the other infants was showing: infants with ASD exhibited the lowest levels of showing compared to LAN (χ²(1,36)=4.21, p< .05), high-risk TD (χ²(1,26)=3.78, p =.05) and low-risk TD (χ²(1,45)=7.11, p<.01). Waving (χ²(1,45)=5.60, p <.05) and protodeclarative pointing (χ²(1,45)=9.74, p<.01) were impaired in ASD versus low-risk TD infants but were similar in ASD, LAN, and high-risk TD infants. Proficiency in giving and raising arms to be picked up was similar across all four groups.

In a binary logistic regression, showing emerged as the strongest predictor of an ASD diagnosis at 24 months of all five gestures (showing: b=-1.77, p < .01).  Given that an infant was proficient in showing at 12 months, the odds were nearly 6 times greater of belonging to one of the control groups than to the ASD group.

Conclusions:   Consistent with other studies (Mitchell et al., 2006), our results show that infants who later develop ASD show deficits in the development of gestures in the first year. While showing, pointing, and waving were impaired in the ASD group, pointing and waving were also impaired in the LAN and high-risk TD groups. Only deficits in showing were specific to the infants with ASD; infants who showed frequently at 12 months were nearly 6 times more likely to be in a non-ASD group than in the ASD group at 24 months. Our findings suggest that individual gestures are strong candidates for inclusion in parent-report screening instruments.  While previous studies often collapsed gestures into a composite score, our results indicate that, given varying trends across specific gestures, a summary score might obscure group differences. More research is needed to further explore developmental profiles of individual gestures in ASD.