Brain obesity
A connection was found between the amount of body fat and the volume of the brain
Maxim Abdulaev, "The Attic"
Scientists scanned 12,000 Britons in a tomograph and saw a link between obesity and brain changes. The greater the weight and fat content, the smaller the volume of gray matter.
Scientists have previously noticed a link between obesity and changes in brain structures. But these studies sinned with a small sample size and the fact that they were looking for a connection between body mass index (BMI) and brain volume. In a new study, scientists from the Netherlands drew attention to the fact that a large BMI can also be in a person who is not obese, but on the contrary, well physically developed. Therefore, scientists conducted a more detailed study, which took into account the percentage of body fat.
The authors of the article used data from participants of a long-term large-scale study UK Biobank, which has been conducted in the UK since 2006 and studies the contribution of heredity and the environment to human health. In total, more than 500,000 people participate in this study, and from 2014 to 2018, the brains of 12,087 participants (approximately equally men and women aged 45 to 76 years) were scanned using diffusion tensor MRI. Their data was used by scientists. They also used information about the percentage of body fat in the participants, which was measured using bioimpedance. It turned out that men have an average fat of 24.4% of body weight, and women - 35.5%.
Next, the scientists compared the data on the structure of the brain obtained using MRI with weight and fat percentage, and then analyzed all this information to find out if these parameters are related and if so, how.
It turned out that there is a connection, and it depends on gender. The percentage of body fat in men negatively correlates with the volume of some parts of the brain consisting of gray matter: the thalamus, caudate nucleus, shell, pale globe, hippocampus and nucleus accumbens. That is, the more fat in the body, the smaller was the volume of all these brain regions.
In women, the link between obesity and brain volume was also traced, but an exceptionally pale ball was affected. And in general, the relationship between the amount of fat and brain volume in men turned out to be stronger – for every 5.5% of body fat, the brain lost an average of 27.2 mm3 of gray matter. Women, on the other hand, paid 11.2 mm3 of gray matter volume for every 6.6% of fat.
MRI of the brain of two study participants. The participant on the left has a body fat content of 13%, the participant on the right has 49%. The participant with a higher fat ratio has a lower volume of subcortical structures of gray matter (Ilona A. Dekkers et al. / Radiology).
In addition, the researchers noticed changes in the structure of the white matter. It turned out that obesity increases its connectivity and reduces the diffusion coefficient. Usually these two parameters signal neurodegenerative diseases and age-related changes, but in reverse order: if connectivity decreases and diffusion increases, then everything is bad.
Perhaps, scientists believe, the brain "shrinks" due to the fact that obesity causes inflammatory processes in the body, and this, as early studies have shown, can harm gray matter. Interestingly, women may be helped by estrogen, which partially protects against metabolic syndrome, a frequent culprit of obesity.
Scientists suggest that a decrease in the mass of gray matter in the brain leads to eating disorders. The fact is that in the departments, the decrease in the volume of which is associated with obesity, there are reward systems for food-related stimuli. It is possible that obesity leads to eating disorders, which, in turn, contributes to further obesity. But this is not accurate – the study does not answer the question whether there is a causal relationship, it only showed a correlation.
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