Summary: A new study reports men and women exhibit different brain activity related to overeating.
A new study of obese people suggests that changes in their brains’ reward regions make them more prone to overeating, and that women and men exhibit different brain activity related to overeating.
Researchers from UCLA found that women who are obese showed more prominent changes in the reward system related to dopamine responsiveness, suggesting that emotion-related and compulsive eating play a larger role in their overeating. Men who are obese showed a different pattern of brain remodeling in sensorimotor regions, a sign that their eating behavior is affected by a greater awareness of gut sensations and visceral responses.
Stress and drug use are known to affect how sex and sex hormones modulate the function of the mesolimbic dopamine system, which is involved in the reward system in the brain. It’s possible that these factors lead to reduced dopamine signaling, according to research. Past studies have also demonstrated how altered processing of rewarding stimuli results in excessive eating. These new findings show that obesity has similar types of effects on the mesolimbic dopamine system.
The researchers collected brain images from 124 individuals (61 males and 63 females) who did not have significant medical or psychiatric conditions. They then calculated how the brain’s reward, sensorimotor, and salience — the brain’s way of making appropriate responses based on biological and cognitive stimuli — networks are related to information flow. The individuals were divided into four groups based on their body mass index and sex: males with high BMI, males with normal BMI, females with high BMI and females with normal BMI.
A person’s sex has not been sufficiently considered as a factor when it comes to devising a plan for treatment of obesity, according to the study’s authors. This research is the first to examine sex-related differences in characterizing the prominence and signaling of brain regions in obesity. A better understanding of sex differences in obesity may allow medical professionals to more precisely tailor individual treatments.
The authors of the study are Arpana Gupta, Dr. Emeran Mayer, Kareem Hamadani, Ravi Bhatt, Connor Fling, Mher Alaverdyan, Cody Ashe-McNalley, Bruce Naliboff, Dr. Kirsten Tillisch, Dr. Claudia Sanmiguel, and Jennifer Labus from UCLA; Carinna Torgerson and John Van Horn from the University of Southern California.
Funding: The research was supported by grants from the National Institutes of Health’s National Institute of Diabetes and Digestive and Kidney Diseases (DK106528, P50 DK064539, R01 DK048351 and P30 DK041301).
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Original Research: Abstract for “Sex differences in the influence of body mass index on anatomical architecture of brain networks” by A Gupta, E A Mayer, K Hamadani, R Bhatt, C Fling, M Alaverdyan, C Torgerson, C Ashe-McNalley, J D Van Horn, B Naliboff, K Tillisch, C P Sanmiguel & J S Labus in Journal of Obesity. Published online April 25 2017 doi:10.1038/ijo.2017.86
Sex differences in the influence of body mass index on anatomical architecture of brain networks
The brain has a central role in regulating ingestive behavior in obesity. Analogous to addiction behaviors, an imbalance in the processing of rewarding and salient stimuli results in maladaptive eating behaviors that override homeostatic needs. We performed network analysis based on graph theory to examine the association between body mass index (BMI) and network measures of integrity, information flow and global communication (centrality) in reward, salience and sensorimotor regions and to identify sex-related differences in these parameters.
Structural and diffusion tensor imaging were obtained in a sample of 124 individuals (61 males and 63 females). Graph theory was applied to calculate anatomical network properties (centrality) for regions of the reward, salience and sensorimotor networks. General linear models with linear contrasts were performed to test for BMI and sex-related differences in measures of centrality, while controlling for age.
In both males and females, individuals with high BMI (obese and overweight) had greater anatomical centrality (greater connectivity) of reward (putamen) and salience (anterior insula) network regions. Sex differences were observed both in individuals with normal and elevated BMI. In individuals with high BMI, females compared to males showed greater centrality in reward (amygdala, hippocampus and nucleus accumbens) and salience (anterior mid-cingulate cortex) regions, while males compared to females had greater centrality in reward (putamen) and sensorimotor (posterior insula) regions.
In individuals with increased BMI, reward, salience and sensorimotor network regions are susceptible to topological restructuring in a sex-related manner. These findings highlight the influence of these regions on integrative processing of food-related stimuli and increased ingestive behavior in obesity, or in the influence of hedonic ingestion on brain topological restructuring. The observed sex differences emphasize the importance of considering sex differences in obesity pathophysiology.
“Sex differences in the influence of body mass index on anatomical architecture of brain networks” by A Gupta, E A Mayer, K Hamadani, R Bhatt, C Fling, M Alaverdyan, C Torgerson, C Ashe-McNalley, J D Van Horn, B Naliboff, K Tillisch, C P Sanmiguel & J S Labus in Journal of Obesity. Published online April 25 2017 doi:10.1038/ijo.2017.86