Pretend Play and Social Engagement in Toddlers at High and Low Genetic Risk for Autism Spectrum Disorder.

Toddlers with an older sibling with autism spectrum disorder (ASD) and low risk (LR) toddlers with typically-developing older siblings were observed during free play with a parent and elicited pretend with an examiner at 22-months. Functional and pretend play, children's social engagement, and parent sensitivity were assessed during free play. Complexity of play was assessed during the elicited pretend task. Toddlers with an ASD diagnosis showed less pretend play across contexts and less social engagement with parents or the examiner than either LR toddlers or high risk toddlers without a diagnosis (HR-noASD). Lower levels of pretend play and social engagement were associated with symptom severity within the high risk group, reflecting emerging ASD in toddlerhood.