Obesity is Associated with Increased Nucleus Accumbens Activation in Postmenopausal Women

Benjamin Ryder, BS

Brigham and Women’s Hospital
Obesity is Associated with Increased Nucleus Accumbens Activation in Postmenopausal Women

Scientific Abstract

Background: Obesity, a major risk factor for diabetes and mood-related disorders, is especially prevalent among postmenopausal women in the United States. Previous neuroimaging studies have shown hedonic eating, one driver of obesity, is characterized by hyperactivity in mesolimbic circuitry. However, whether dysregulation of this circuitry is associated with obesity in postmenopausal women has not been examined. To address this gap, we investigated mesolimbic activation during food reward anticipation and receipt in postmenopausal women with and without obesity.

Methods: 19 healthy weight postmenopausal women (HW; BMI<25; mean age=55.7; SD=2.7; mean BMI=22.7; SD=1.9) and 14 postmenopausal women with obesity (OB; BMI>30; mean age=54.7; SD=2.8; mean BMI=34.2; SD=4.0) underwent functional magnetic resonance imaging (fMRI) during a Food Incentive Delay (FID) task. A fasting blood draw was obtained to assess metabolic hormones and glucose. Brain activation during food anticipation and food receipt was analyzed in the following regions of interest (ROI): nucleus accumbens (NAcc), caudate, putamen, and ventral tegmental area (VTA).

Results: Relative to the HW group, the OB group showed increased fasting glucose (p=0.01), fasting insulin (p<0.01), and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), p<0.01. ROI analyses revealed no group differences during food anticipation. During food receipt, the OB group exhibited higher activation than the HW group in bilateral NAcc [L: p(FWE)=0.03; R: p(FWE)=0.04]. Activation in the HW group was positively correlated with fasting insulin (L NAcc: r=0.62, p<0.01; R NAcc: r=0.75, p<0.01) and HOMA-IR (L NAcc: r=0.58, p=0.01; R NAcc: r=0.71, p<0.01). No such correlations were present in the OB group (ps > 0.10).

Conclusion: These preliminary results suggest that obesity among postmenopausal women is associated with increased NAcc activation during the consummatory component of food reward processing, and a decoupling of NAcc activation from metabolic factors. These results lend insight into mesolimbic functioning in postmenopausal women during a food reward task.

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research Areas

Authors

Benjamin T. Ryder, BS, Jessica N. Busler, PhD, Julia Hall, BS, Hyeonmin Ahn, PhD, Diego A. Pizzagalli, PhD, Daniel G. Dillon, PhD, Laura M. Holsen, PhD

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