Objectives: To use a longitudinal dataset with monthly time points between 12 and 36 months to identify patterns in age of acquisition of social-communicative behaviors, and patterns of relationships between these behaviors; and to examine their predictive value in toddlers.
Methods: Participants were identified from an ongoing longitudinal study, which follows children monthly who have been referred for possible autism, or have a sibling with ASD. Data were used from 25 children who had at least five administrations of the Autism Diagnostic Observation Schedule – Toddler module (ADOS-T) between 12 and 30 months. At the most recent assessment, 12 children were diagnosed with an autism spectrum disorder, 9 with a non-spectrum disorder, and 4 as typically developing (19 males, 6 females). The mean age of first ADOS-T assessment was 14.20 months (2.27).
Results: Analyses indicated predictable patterns of acquisition (defined by 2 scores of 0 on individual items in successive ADOS-T administrations) of many social-communicative behaviors (e.g. Response to Name, Response to Joint Attention, Initiation of Joint Attention, Requesting, and Integration of Gaze and Other Behaviors). A progression occurred from partial to full acquisition for many skills. Individual differences in behaviors and children will be examined in detail using growth curves.
Conclusions: Timing of acquisition of different behaviors was similar for some skills (e.g. Response to Joint Attention and Integration of Gaze and Other Behaviors) and varied considerably for others (e.g. Response to Name). Implications in the very early diagnosis and treatment of children with ASD will be discussed.