Divergent neural substrates of inhibitory control in binge eating disorder relative to other manifestations of obesity

Abstract

Objective: An important endeavor involves increasing our understanding of biobehavioral processes underlying different types of obesity. The current study investigated the neural correlates of cognitive control (involving conflict monitoring and response inhibition) in obese individuals with binge eating disorder (BED) as compared to BMI-matched non-BED obese (OB) individuals and lean comparison (LC) participants. Alterations in cognitive control may contribute to differences in behavioral control over eating behaviors in BED and obesity.

Design and methods: Participants underwent functional magnetic resonance imaging while completing the Stroop color-word interference task.

Results and conclusions: Relative to the OB and LC groups, activity in the BED group was differentiated by relative hypoactivity in brain areas involved in self-regulation and impulse control. Specifically, the BED group showed diminished activity in the ventromedial prefrontal cortex (vmPFC), inferior frontal gyrus (IFG), and insula during Stroop performance. In addition, dietary restraint scores were negatively correlated with right IFG and vmPFC activation in the BED group, but not in the OB or HC groups. Thus, BED individuals' diminished ability to recruit impulse-control-related brain regions appears associated with impaired dietary restraint. The observed differences in neural correlates of inhibitory processing in BED relative to OB and LC groups suggest distinct eurobiological contributions to binge eating as a subgroup of obese individuals.

Figure 1. Main Effect of Stroop Task Performance

Change in mean fMRI BOLD signal on Stroop-effect, collapsed across group, contrasting incongruent trials with congruent trials in N=35 participants. The contrast map is thresholded at an uncorrected level of p < 0.01 two-tailed and FWE-corrected at p < 0.05 with a cluster threshold of 28. Blue/green color demonstrates areas of significant differences between incongruent and congruent conditions where relatively less activity occurs in the incongruent condition. Yellow/orange color indicates areas of relative greater activity during the incongruent condition. The right hemisphere of the brain is on the right side. Saggital view is represented at x=0, coronal view at y=0 and axial view at z=0.

Figure 2. Group Differences in Brain Activity during Stroop Task Performance

Maps show contrasts between the three experimental groups: obese individuals with binge eating disorder (BED; n=11), obese individuals without binge eating disorder (OB; n=13) and lean comparison (LC) participants (n=11) during incongruent vs congruent conditions of the Stroop. The contrast map is thresholded at an uncorrected level of p < 0.05 two-tailed and family-wise-error-corrected at p < 0.05 with a cluster threshold of 90. Orange/yellow color indicates areas of increased activity between groups. Blue areas represent areas of decreased activity between groups. The right hemisphere of the brain is on the right. Images are unmasked.

Figure 3. Correlations between Restraint Scores and Brain Activity during Stroop Task Performance

Maps show correlations between eating restraint scores on the EDE-Q and activity during Stroop performance in the three experimental groups: a) obese individuals with binge eating disorder (BED; n=11), b) obese individuals without binge eating disorder (OB; n=13) and c) healthy control lean comparison (LC) participants (n=11). The contrast map is thresholded at an uncorrected level of p < 0.05 two-tailed and family-wise-error-corrected at p < 0.05 with a cluster threshold of 90. Orange/yellow color indicates a positive correlation and blue areas represent areas of negative correlations. The right hemisphere of the brain is on the right. Images are unmasked.