Impact of obesity on brain structure: A critical review of the evidence from Magnetic Resonance imaging studies.

Obesity has been a global health concern for a few decades. A closely studied consequence of obesity has not only been limited to diabetes and cardiovascular disease but also related to the brain and nervous system. The systemic low-grade inflammatory status of obesity is capable of being translated to inflammation of the brain, causing several structural and functional changes and leading to cognitive disorders. The frontal lobe of the brain is the most susceptible to structural changes due to obesity. Common structural changes associated with higher BMI and higher fat deposition are the integrity of grey matter and reduction of global brain volume due to neuronal loss and demyelination. Besides grey matter volume reduction, the frontal and temporal parts of the brain had shown significant cortical thinning with increased BMI. White matter integrity was found to be compromised, and it was even more extensive with lower functional anisotropy. The increased consumption of food in obesity was a consequence of increased activation of reward-related areas of the brain during food processing and lack of inhibitory responses to food in the Dorsolateral Prefrontal Cortex. Comparing the changes across age groups, it has been found that early intervention in weight management can inhibit the onset of cerebral complications in later life. A cross-country comparison has raised a concern to initiate more research on obesity and brain health in Asians, especially Indians, considering their ethnic vulnerability to visceral adiposity. Amidst differences in obesity diagnosis, neuroimaging can provide insightful biomarkers to understand obesity in-depth.