Abstract
BACKGROUND: Gesture difficulties have been reported in later-born siblings of children with autism spectrum disorder (ASD). Careful observation of gesture development during the first two years of children at elevated likelihood (EL) of developing ASD may identify behavioral indicators that facilitate early diagnosis. METHODS: This study enrolled 47 EL infants and 27 low-likelihood (LL) infants to explore gesture developmental trajectories and the predictive value of gesture to expedite the early detection of core characteristics of ASD. Gesture frequency, communication function, and integration ability were observed and coded from a semi-structured assessment administered longitudinally across 9-19 months of age. We conducted the Autism Diagnostic Observation Schedule assessment at 18-19 months for ASD's core characteristics. RESULTS: The development of joint attention (JA) gestures was slower in the EL than in the LL group. The trajectories of the two groups began to diverge at 14-18 months. Children who reached the diagnostic cutoff point for ASD showed reductions in social interaction gestures at 12-13 months, in gestures integrated with any two communication skills (G-M) at 15-16 months; and in gestures integrated with eye contact (G-E) at 18-19 months. Overall gesture and G-M integration were associated with an overall ADOS communication and social interaction score. CONCLUSIONS: The developmental trajectories of JA gestures of EL and LL children differed. G-M gestures represent early indicators that may be a predictor of ASD.