Altered neural reward processing is associated with reward-related decision-making in adolescents with severe obesity

Abstract

Obesity is associated with altered food-related reward processing, but its impact on non-food reward remains unclear. This question is both timely due to rising rates of severe obesity and important because adolescence is a period of heightened reward seeking behavior. We used computational modeling and functional magnetic resonance imaging (fMRI) to examine monetary reward processing using classic experimental tasks in 35 adolescents (14-18 years-old, 13 male) with severe obesity (OB; n=18) and without obesity (nonOB; n=17). Participants completed the Balloon Analog Risk Taking Task (BART) to assess reward-related decision-making and the Monetary Incentive Delay (MID) task to assess neural correlates of reward anticipation. BART model-based parameters revealed no differences in reward sensitivity but less adaptive decision-making (response consistency) in OB compared to nonOB. Other metrics (e.g., number of balloons popped, number of pumps, and total points) did not differ between groups. During MID reward anticipation, OB had lower activation than nonOB in ventral tegmental area (VTA) and prefrontal cortex, canonical regions for reward and cognitive control, respectively. Weight status moderated associations between VTA activation and BART metrics such that higher VTA activation was associated with more risky decision-making (more popped balloons) in OB but not nonOB. Functional connectivity of VTA with right inferior frontal gyrus (IFG) and left superior temporal gyrus (STG) was greater higher in OB than nonOB. Associations between value-related VTA-STG connectivity and BART metrics were moderated by weight status such that higher connectivity was associated with greater number of pumps and points for nonOB and less risky decision-making for OB. Therefore, differences in activation and connectivity between groups may suggest differences in decision-making strategies. Together, findings reveal that VTA, prefrontal, and temporal engagement during monetary reward anticipation differs in OB and nonOB adolescents and may contribute to individual differences in reward-related decision-making. Such domain-general alteration of reward processing may have far reaching consequences, not only for food intake but also functions central to motivational behavior such as learning and socialization during adolescence, a sensitive period in development. These findings highlight the importance of considering reward more broadly when designing and tailoring behavioral interventions in adolescent obesity