Monetary reward processing in obese individuals with and without binge eating disorder

Abstract

Background: An important step in obesity research involves identifying neurobiological underpinnings of nonfood reward processing unique to specific subgroups of obese individuals.

Methods: Nineteen obese individuals seeking treatment for binge eating disorder (BED) were compared with 19 non-BED obese individuals (OB) and 19 lean control subjects (LC) while performing a monetary reward/loss task that parses anticipatory and outcome components during functional magnetic resonance imaging. Differences in regional activation were investigated in BED, OB, and LC groups during reward/loss prospect, anticipation, and notification.

Results: Relative to the LC group, the OB group demonstrated increased ventral striatal and ventromedial prefrontal cortex activity during anticipatory phases. In contrast, the BED group relative to the OB group demonstrated diminished bilateral ventral striatal activity during anticipatory reward/loss processing. No differences were observed between the BED and LC groups in the ventral striatum.

Conclusions: Heterogeneity exists among obese individuals with respect to the neural correlates of reward/loss processing. Neural differences in separable groups with obesity suggest that multiple, varying interventions might be important in optimizing prevention and treatment strategies for obesity.

Figure 1

Group differences on the Monetary Incentive Delay Task in ventral fronto-striatal areas in obese individuals with binge eating disorder (BED) (n = 19), obese individuals without BED (OB) (n = 19), and a lean comparison (LC) (n = 19) group at z = −17, −11, −6. Brain activation maps demonstrate differences in the A2 winning phase (A2W) (associated with the anticipation of potentially winning money), the A2 losing phase (A2L) (associated with the anticipation of potentially losing money), the outcome winning phase (OCW) (associated with the receipt of a monetary reward), and the outcome losing phase (OCL) (associated with the loss of money). All contrast maps are thresholded at an uncorrected level of p < .05 two-tailed and family-wiseerror-corrected at p < .05. Blue color demonstrates areas where subjects show relatively less activation, and red color indicates where participants show relatively greater activation. The right side of the brain is on the right.

Figure 2

Coronal view of ventral striatal regions of interest (ROIs) with coordinates reported by Knutson and Greer (43). (A) Blue spots indicate a 5-mm sphere around the ventral striatum on the left [−12, 10,−2] and right [10, 8, 2] sides. (B) Coronal slice y = 10 demonstrates whole brain contrast between BED and OB groups during the A2 winning phase. Graphs depict percentage blood oxygen level–dependent (BOLD) signal change extracted from each 5-mm ROI on the right and left sides for the BED (blue) and OB (red) groups. (C) Coronal slice y = 10 demonstrates whole brain contrast between OB and LC groups during the A2 winning phase. Graphs depict percentage BOLD signal change extracted from each 5-mm ROI on the right and left sides for the OB (red) and LC (green) groups. (D) Coronal slice y = 10 demonstrates whole brain contrast between BED and LC groups during the A2 winning phase. Graphs depict percentage BOLD signal change extracted from each 5 mm ROI on the right and left sides for the BED (blue) and LC (green) groups. The right side of the brain is on the right. Abbreviations as in Figures 1 and 2.

Figure 3

Coronal view of ventral striatal ROIs with coordinates based on reward processing findings by Breiter et al. (15). (A) Blue spots indicate a 6-mm sphere around the ventral striatum on the left (−12, 7, −10) and right (12, 7, −10) sides. (B) Coronal slice y = 10 demonstrates whole brain contrast between BED and OB groups during the A2 winning phase. Graphs depict percentage BOLD signal change extracted from each 6-mm ROI on the right and left sides for the BED (blue) and OB (red) groups. (C) Coronal slice y = 10 demonstrates whole brain contrast between OB and LC groups during the A2 winning phase. Graphs depict percentage BOLD signal change extracted from each 6-mm ROI on the right and left sides for the OB (red) and LC (green) groups. (D) Coronal slice y = 10 demonstrates whole brain contrast between BED and LC groups during the A2 winning phase. Graphs depict percentage BOLD signal change extracted from each 6-mm ROI on the right and left sides for the BED (blue) and LC (green) groups. The right side of the brain is on the right. Abbreviations as in Figures 1 and 2.