Study finds possible link between obesity and brain changes

A recent study using sophisticated MRI technology has found that individuals who have higher levels of body fat show differences in their brain’s form and structure, including smaller volumes of gray matter.  Published in the journal Radiology, these findings contribute to the information we have of our understanding of the connection between obesity and health consequences such as dementia.

These findings are concerning as obesity is one of the most challenging public health problems facing our world today. It is already known that carrying excess body weight increases the risk for cardiovascular disease and type 2 diabetes.  Now, this study, along with others, continues to show an association of an increased risk of accelerated cognitive decline and dementia, suggesting that obesity may causes changes to the brain.

For the study, researchers from Leiden University Medical Center in Netherlands analyzed gray and white matter in the brains of around 12,000 people using MRI results from the UK Biobank study.  Discovered was a significant link between higher levels of fat all over the body and smaller volumes of the important structures of the brain. Previous research has shown that associated body fat, particularly in the belly, with lower brain volumes. For this current study, it was also found that men who have higher levels of body fat are likely to have smaller volumes of gray matter in the brain. For women, the result of a higher percentage of total body fat affected the globus pallidus.  These findings of differences between men and women suggest that gender is an important modifier of the link between fat percentage and the size of specific brain structure.

What these results may demonstrate could be significant. Smaller gray matter volume suggests loss of neurons, and changes to the white matter would adversely affect the transmission of signals within brain networks. Since the smaller subcortical gray volumes are also known to play a role in the food-reward circuitry, these changes may also make it more difficult for obese people to control their weight.

While it is not known the precise reason why obesity may have an adverse effect on the brain, research has shown that obesity itself can cause low-grade inflammation having harmful effects on brain tissue. The evidence shows that cellular responses produced in the brain due to inflammation may be the reason for these effects.

The researchers with the study stated that for future research, there is an interest to see if differences in body fat distribution are related to differences in brain morphological structure, since visceral fat found deep within the abdomen, is a known risk factor for metabolic diseases and is linked to low-grade inflammation.