Weight gain and brain development in the ABCD study cohort: A decade of insight and the road ahead.

Currently, childhood obesity affects 20% of US youth, and estimates are climbing. This suggests that risk factors contributing to its development and maintenance are poorly understood. As the brain plays an important role in food intake, it has emerged as a potential key driver of excess weight gain. Conversely, weight gain is thought to have detrimental effects on the brain particularly among regions that control food intake, thus, creating a vicious cycle of overeating. This review synthesizes recent findings from the Adolescent Brain Cognitive Development (ABCD) Study®, a large national, longitudinal, multimodal dataset. ABCD's unparalleled longitudinal imaging, dense behavioral phenotyping, and multi-omic data have uniquely enabled researchers to move beyond cross-sectional correlations in small homogeneous samples, and test temporal, bidirectional, associations between neurodevelopment and weight gain. Studies have begun to suggest that structural and functional differences in the brain from ages 9-to-12-years-old relate to body mass index (BMI), weight gain, and cognitive outcomes, cross-sectionally and longitudinally. Here, we discuss potential mechanisms of these associations, including some environmental (e.g., socioeconomic status, resources), lifestyle (e., sleep, physical activity, diet), and heritable (e.g., genetics, prenatal programming) factors that may exacerbate risk and maintenance. While these studies begin to shed light on these associations, we also focus on gaps in knowledge and how the ABCD Study data can be further leveraged to probe into mechanistic pathways and inform prevention and intervention strategies. With this review, we highlight ways in which the scientific community can collaborate to continue to advance our knowledge on this topic.