Using the Brief Observation of Social Communication Change (BOSCC) to characterize the heterogeneous presentation of social communication and restrictive repetitive behaviors in young children with Down syndrome.

1. Elizabeth Kolln (Down Syndrome Program, Boston Children's Hospital)
2. Carol Wilkinson (Boston Children’s Hospital, Developmental Medicine Center)
3. Rebecca Thomas (Boston Children’s Hospital, Developmental Medicine Center)

Correspondence: elizabeth.kolln@childrens.harvard.edu

Children with DS often show many social communication strengths, including eye contact, gesture use, directed vocalizations, and facial expressions (La Valle et al., 2025). However, rates of autism are also increased in DS, with estimates ranging from 16-42% (DiGuiseppi et al., 2010; Godfrey et al., 2019; Spinazzi et al., 2023). Given the heterogeneity of DS and the overlap in symptoms between intellectual disabilities and autism (e.g., restrictive repetitive behaviors (RRBs), atypical sensory behaviors; Glennon et al., 2017), further characterization of social communication and repetitive behaviors within DS is needed to improve accurate and early identification of autism in DS, and better understand how these behaviors may or may not be associated with developmental outcomes.

The Brief Observation of Social Communication Change (BOSCC) is a coding scheme for assessing changes in autistic traits in children, including both social communication and RRBs. The BOSCC is relatively easy to become reliable on, and can be applied to 10-minute video clips from caregiver-child interactions, making it a flexible tool for research (Byrne & Lord, 2023). Few studies have assessed the utility of the BOSCC in disorders of intellectual disability. The BOSCC has been piloted on populations with Fragile X Syndrome, in which it was found to be a viable measure of social communication traits (Shaffer et al., 2022), but less reliable for RRBs. The feasibility and utility of the BOSCC in DS has yet to be determined.

The present study seeks to assess how the BOSCC characterizes the heterogeneity of social communication and RRBs in toddlers and preschoolers with DS (n = 34). Latent class analyses will be conducted to determine how social communication and other behaviors coded by the BOSCC cluster in subgroups of children with DS. ANOVAs will determine how these clusters of BOSCC codes are associated with language and cognitive skills, two developmental domains that are especially impacted in children with co-occurring autism and DS (Dimachkie Nunnally et al., 2021). Findings from the DS cohort will also be compared to BOSCC codes from a cohort of 37 similarly-aged autistic children to further investigate which symptoms overlap between autism and DS. This presentation will include an overview of the BOSCC and how it can be applied to DS. Preliminary findings will also be presented.