Developmental Functioning of Infants and Toddlers with Autism and Down Syndrome

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social communication, as well as restricted interests and repetitive behaviors. Approximately 10% of individuals with ASD also have comorbid genetic or chromosomal conditions, like Down Syndrome (DS). While it was once believed that DS and ASD rarely co-occurred, it has been demonstrated that it is not uncommon for children with DS to also meet criteria for ASD. Due to the difficulties in differentiating between impairments associated with intellectual disability (ID) and ASD symptomology, DS often leads to delayed or misdiagnoses of ASD. This can interfere with early intervention services and appropriate educational placements. While prior research has compared developmental functioning in children with ASD and DS, no studies have examined the impact of ASD risk and DS on developmental functioning in infants and toddlers under the age of 3. Utilizing the Baby and Infant Screen for Children with aUtIsm Traits-Part 1 (BISCUIT-Part 1) and the Battelle Developmental Inventory, Second Edition (BDI-2), the current study aimed to expand the existing literature by investigating the effects of ASD risk and DS on developmental functioning in infants and toddlers. The current study compared three groups consisting of 46 toddlers each: ASD screen positive only without co-occurring DS (ASD+), DS screen negative (DS-), and DS screen positive (DS+). The results of the current study revealed significant group differences in the overall developmental functioning, as well as each developmental subdomain of the BDI-2. These findings support the need for early screening and identification of ASD among those with genetic conditions