Developmental trajectories of adaptive behavior in autism spectrum disorder: a high‐risk sibling cohort

BACKGROUND: Children with autism spectrum disorder (ASD) often experience impairments in adaptive behavior. METHODS: Developmental trajectories of adaptive behavior in ASD were examined in children from high-risk (siblings of children diagnosed with ASD, n = 403) and low-risk (no family history of ASD, n = 163) families. Children were assessed prospectively at 12, 18, 24, and 36 months of age using the Vineland Adaptive Behavior Scales and underwent a blind independent diagnostic assessment for ASD at 36 months of age. RESULTS: The semi-parametric group-based modeling approach using standard scores on the Adaptive Behavior Composite revealed three distinct developmental trajectories: (a) Group 1 (21.2% of sample) showed average performance at 12 months and a declining trajectory; (b) Group 2 (52.8% of the sample) showed average performance at 12 months with a slightly declining trajectory; and (c) Group 3 (26.0% of the sample) showed a higher level of adaptive behavior at 12 months and a stable trajectory. The Mullen Scales of Early Learning Early Learning Composite and the Autism Observation Scale for Infants total score at 6 and 12 months predicted trajectory membership. CONCLUSIONS: The results emphasize heterogeneous development associated with ASD and the need for interventions tailored to individual presentations.