Sleep Disturbances, Obesity, and Cognitive Function in Childhood: A Mediation Analysis

Background: Childhood cognitive development is influenced by biological and environmental factors. One such factor, obesity, impairs cognitive development and is associated with sleep disturbances. Objectives: We aimed to examine the mediating role of sleep disturbances on the relation between BMI and cognitive function in children. Methods: A total of 9951 children aged 9-10 y were included in this cross-sectional study. Children were recruited from the longitudinal ABCD (Adolescent Brain Cognitive Development) Study. Cognitive development was assessed using metrics for fluid, crystallized, and total cognitive function. Mediation analyses were conducted via linear regression modeling, with adjustment for potential confounders (sex, age, ethnicity, household income, parental education, and self-reported physical activity) for each of the 3 outcomes. Mediation significance was determined by bootstrapping. Results: A statistically significant inverse association was found between BMI and total (beta = -0.41, P < 0.001) and fluid (beta = -0.49, P < 0.001) cognition, but not for crystallized cognition. Total sleep disturbances partially mediated the association between BMI and fluid cognition (indirect effect: -0.02, P = 0.002; proportion of the total effect: 0.05, P = 0.002), but no mediation was found in the association between BMI and total cognition. Conclusions: Sleep disturbances partially mediate the effect of childhood obesity on cognitive function, particularly in fluid cognitions. Future work is necessary to understand the effects of sleep disturbances and obesity on reduced childhood cognition throughout time, predominantly across the life course.