Navas JFN, et al. - The aim of this study was to explore the correlation between body fat levels and brain reward system responsivity to general (monetary) rewards in male and female adolescents. Higher adiposity is linked to hypo-responsivity of somatosensory regions during general (monetary) reward feedback in adolescents. Data demonstrates that adolescents with excess weight have blunted activation in somatosensory regions involved in reward feedback learning.

Methods

• Researchers assessed 68 adolescents (34 females; mean age [standard deviation]=16.56 [1.35]) for body fat levels with bioelectric impedance, and underwent a functional magnetic resonance imaging (fMRI) scan during the Monetary Incentive Delay (MID) task.
• The MID task reliably elicits brain activations associated with two fundamental aspects of reward processing: anticipation and feedback.
• They performed regression analyses to analyze the correlation between body fat and brain reward system responsivity during reward anticipation and feedback, while controlling for sex, age and socioeconomic status.
• They further examined the moderating impact of sex on the relationship between fat levels and brain responsivity measures.
• Furthermore, brain imaging analyses were corrected for multiple comparisons, with a cluster-defining threshold of P

Results

• Evidence showed that higher body fat levels were correlated with lower activation of the primary somatosensory cortex (S1) and the supramarginal gyrus during reward feedback after controlling for key sociodemographic variables.
• While they did not observe significant correlations between body fat and brain activations during reward anticipation, S1/supramarginal gyrus activation during feedback was linked to increased negative prediction error, i.e., less reward than expected, in illustrative post-hoc analyses.
• In addition, sex did not significantly moderate the correlation between body fat and brain activation in the MID task.