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How does Obesity Affect the Brain?

Known as one of the most common worldwide health issues, obesity affects all organs, including the brain. Many people are not aware that the term ‘obesity’ is not limited to just the weight gain and high BMI, but with low-grade inflammation as well. Obesity is also associated with the metabolic syndrome, which is a cluster of conditions including increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol or triglyceride levels. All of these increase the chance of diabetes, stroke, and heart disease. Neuroinflammation caused by obesity has shown to affect many areas of the brain, including the hypothalamus, hippocampus, cortex, brainstem, and amygdala. Research conducted in this area is very important as obesity-induced neuroinflammation has been associated with increased occurrence of central disorders such as depression and impaired cognitive function.

Guillemot-Legris and Muccioli have shown that the neuroinflammation caused by obesity depends on the type of diet and how long the diet lasted. It has also been shown that neuroinflammation does not occur at the same rate in different brain regions, and it depends on the area. Miller and Spencer have also shown that the high-fat diet leads to systemic inflammation and excess circulating free fatty acids. The means that free fatty acids, immune cells as well as circulating cytokines reach the brain (especially the hypothalamus) and integrate the inflammation in the neurones. This also includes proliferation of the microglia. The hypothalamus, along with other regions of the brain, suffers synaptic remodelling and, therefore, neurodegeneration occurs, altering the internal hypothalamic circuitry and hypothalamic outputs to other brain regions.

Stanek et al. have discovered that obesity also leads to a decrease in white matter integrity, which leads to reduced neural transmission speed and slowed information processing as well as executive and working memory dysfunction. Even though the study of white matter in obese individuals is quite limited,  the findings so far have shown that age is also a defining factor. In older individuals, obesity is more common and, therefore, so is the decrease in white matter. Prospective studies are needed for further evidence in this field, as it can be crucial to understanding the related diseases.

 

Guillemot-Legris, O., and G. G. Muccioli. “Obesity-Induced Neuroinflammation: Beyond the Hypothalamus.” Trends in Neurosciences. U.S. National Library of Medicine, Apr. 2017. Web. 14 May 2017.

Guillemot-Legris, Owein, and Giulio G. Muccioli. “Obesity-Induced Neuroinflammation: Beyond the Hypothalamus.” Trends in Neurosciences 40.4 (2017): 237-53. Web.

Stanek, Kelly M., Stuart M. Grieve, Adam M. Brickman, Mayuresh S. Korgaonkar, Robert H. Paul, Ronald A. Cohen, and John J. Gunstad. “Obesity Is Associated With Reduced White Matter Integrity in Otherwise Healthy Adults*.” Obesity 19.3 (2010): 500-04. Web.

Edited by: Kaylynn Crawford and Daryn Dever