Thursday, April 3, 2025
4/3/2025
Developmental trajectories of reinforcer pathology and childhood obesity - ABSTRACT The percentage of children with obesity increases throughout development. Obesity results from a positive energy balance, which suggests the energy balance gap increases as children age. Reward systems that drive the motivation to eat or be physically active, conceptualized as food and activity reinforcement, mature throughout development, potentially exerting a greater influence on adolescents than younger children's decision-making. Executive functions that allow youth to focus on long-term goals rather than immediate gratification are not fully developed until early adulthood. Reinforcer pathology theory considers the balance between the reinforcing value of food and physical activity and the need for immediate versus delayed gratification (as measured by delay discounting). The differential trajectories of reinforcement and delay discounting may be essential to understanding the increase in obesity from childhood through adolescence. Reinforcer pathology theory can be used to understand how changes in food and activity reinforcement drive eating and activity in the context of a developing executive function system that regulates these processes. Food is a powerful, primary reinforcer that activates brain reward pathways and motivates people to eat. Physical activity is also a powerful reinforcer that motivates people to be active. Obesogenic environments contribute to food and activity reinforcement, through excess caloric intake and a sedentary lifestyle, which may have opposing developmental trajectories, as energy intake and food reinforcement may increase while physical activity decreases. Decreases in physical activity begin around ages 9-10 and continue throughout adolescence, which suggests a reduction in the motivation to be active. Delay discounting, which can regulate the need for immediate gratification, improves from childhood to adolescence through adulthood. This study will fill a gap in assessing developmental trajectories of food and activity reinforcement and delay discounting in children from 9-16 years-of-age, which captures a developmental period with an increase in obesity prevalence. The study uses an innovative cohort sequential design to assess developmental trajectories of the reinforcing value of food and activity, delay discounting, dietary intake and physical activity, zBMI and body fat (Aim 1); assess the relationships between developmental trajectories of food and activity reinforcement, delay discounting, dietary intake and physical activity with the trajectories of zBMI and body fat (Aim 2); and test environmental and socioeconomic factors that can influence the developmental trajectories of zBMI and body fat through trajectories of food and activity reinforcement, dietary intake and physical activity, and delay discounting (Aim 3). This study will be the first to use reinforcer pathology theory to assess how developmental trajectories of food and activity reinforcement, delay discounting and eating and physical activity relate to the development of obesity throughout childhood and adolescence. This information can guide pediatric obesity interventions tailored to developmental stages and behavioral phenotypes.
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