PROJECT SUMMARY ABSTRACT Children with Down syndrome (DS) are disproportionately affected by the obesity epidemic, presenting a prevention challenge that is currently unmet. Despite improved life expectancies, people with DS experience poor health.10 Children and adults with DS have significantly higher rates of overweight/obesity (OW/OB) than those with intellectual disability from other causes11 or the general population.12 These risks are rooted in childhood, with rapid increases in OW/OB observed between ages 2 and 6 years in children with DS2–4 and childhood OW/OB conferring a higher risk for OW/OB in adulthood.2,3 However, research examining young children with DS+OW/OB has primarily focused on prevalence rates using retrospective clinical data, with minimal attention to modifiable prevention targets.2,11,13 Consequently, critical questions regarding how DS phenotypic factors such as co-occurring conditions, motor delays, and feeding challenges contribute to OW/OB risk remain unanswered. Despite being a specific, high-risk population for obesity, no prospective, longitudinal DS research has comprehensively characterized OW/OB predictors to guide effective prevention in early childhood when such efforts may enhance downstream health outcomes. Bridging this knowledge gap recently highlighted by prominent DS researchers,18 our team representing expertise in early development in DS, nutrition, and obesity in DS, physical activity (PA), and sleep, will use a longitudinal design to identify early OW/OB prevention targets for young children with DS. Using a staggered wave approach, we will enroll and assess 1/3 of the sample in Wave 1/Y1, with annual follow-up visits (+ 1 month) in Y2&3, using the same approach for Wave 2 (Y2-4) and Wave 3 (Y3-5), thus reducing recruitment demands over time and sites (total project n=160). At T1-3, we will collect data on (a) child factors—objectively measured PA, motor abilities (gross, fine, motor planning), sleep, and weight/height, plus caregiver-reported child dietary intake (energy, macronutrients, and dietary quality), child developmental and medical history, and feeding abilities; and (b) caregiving factors—caregiver feeding and PA practices, family dynamics, caregiver weight/height, and SES. At T1, we will recruit caregivers and their child with DS chronological ages 18-40 months, who walk 15+ feet independently. The age range ensures participant ages align with: (1) the full range of developmental variability expected in children with DS given that 95% of children with DS reach this walking milestone between 18-40 months (median = 24 months),5 and (2) observed weight gain increases between 2 to 6 years of age in DS,2–4 with 4-6 year-olds 61% more likely to have OB than those aged 2-3 years.2 The overarching project goal is to understand variability in risks for OW/OB in DS and identify prevention targets in young children with DS. Our long-term goal is to develop and deliver obesity prevention in early childhood to reduce risks for OW/OB and associated medical sequelae across the lifespan for individuals with DS.

Project Narrative Children with Down syndrome are disproportionately affected by the obesity epidemic, presenting a prevention challenge that is currently unmet. For toddlers and preschoolers with Down syndrome, this project examines how motor skills development, feeding abilities, co-occurring conditions, dietary intake, and the family context provide protection or risks for overweight/obesity. The overarching goal of this project is to identify targets for effective prevention in early childhood when such efforts may enhance downstream health outcomes for those with Down syndrome.