Neural Mechanisms of Food And Monetary Rewards and Their Relation to Overeating in Children

摘要

Currently, 17% of American children are considered obese. Yet, the reasons as to why some children are more susceptible to overeating are poorly understood. Deficits in decision-making abilities, such as how the brain responds to rewards in regions implicated in reward processing and inhibitory control, have been linked to obesity in children. This suggests that fundamental differences in decision-making abilities may be a risk factor for overeating, and potentially, a target for prevention. However, it is currently unknown if deficits in key decision-making regions relate to objectively measured food intake. This dissertation adds to the literature by investigating how brain determinants of decision making for food and money relate to food intake and weight status in a cohort of children 7- 11-years-old. Neural correlates of decision-making were assessed by having children undergo a functional magnetic resonance imaging (fMRI) scan while completing a modified cardguessing task that assessed anticipating and winning food and monetary rewards. Behavioral correlates of decision-making were assessed with a Go/Nogo (reactive inhibitory control) task with and without food and monetary reward incentives. Objectively measured food intake was assessed using three different laboratory test meals aimed at measuring different aspects of eating behavior. Results from all three papers identified potential decision-making mechanisms that were associated with obesity risk development. For the first time, we showed that how the brain responds to rewards might play a crucial role in identifying behaviors that can lead to future weight gain. Brain response to food vs. money rewards in regions associated with emotion, reward processing, and inhibitory control predicted food-approach behaviors and laboratory measures of overeating independently of how much a child weighed. In addition, weight status negatively correlated with reactive inhibitory control performance during a reward incentivized Go/Nogo task. Reactive inhibitory control was not related to food intake under controlled settings, however, since weight status was related to reactive inhibitory control this might provide insight into how these decisionmaking processes relate to overeating outside of the laboratory. Altogether, findings from this dissertation identified some of the neural mechanisms contributing to maladaptive eating behavior. This dissertation provides the groundwork for understanding how cognitive mechanisms contribute to eating behavior in children, providing insight into why some children are more susceptible to overeating than others. Understanding how reward processing and inhibitory control relates to food intake in children may be the key to increased success of intervention and prevention programs.