The Relation of Impulsivity and Obesity: A Neuroimaging Analysis
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The current study examined the relation of impulsivity and obesity in three neuroimaging studies using MRI techniques to test the hypothesis that deficits in brain regions responsible for inhibitory control are associated with obesity. The first study used voxel-based morphometry (VBM) to explore volumetric differences in lean, overweight, and obese women (N=83) and found that BMI was negatively correlated with grey matter (GM) in the insula, frontal operculum, and inferior frontal gyrus. BMI was positively correlated with white matter (WM) in the fusiform gyrus, parahippocampal gyrus, Rolandic operculum, and dorsal striatum. Genetic alleles for dopamine expression moderated these relations. Additionally, less GM in the superior frontal gyrus predicted future increases in BMI. The second study used VBM to examine differences between lean adolescents at risk versus not at risk for obesity (N=54). There were no regional GM or WM differences based on risk status. There were also no regional differences that predicted weight gain over 1-year follow-up. Additionally, genetic alleles for dopamine expression did not moderate any of these regions. These findings suggest that volumetric differences may emerge after excessive weight gain. Finally, the third study used a psychophysiological interaction analysis to test functional connectivity between prefrontal and limbic regions as a function of BMI in lean, overweight, and obese women (N=37) during a go/no-go task. There was no functional connectivity found in seed regions in relation to BMI. Implications for intervention and future research are discussed.