Obesity is known to increase a person’s risk for a host of diseases, including cardiovascular problems, diabetes, and even cancer. Now a new study finds that being overweight can age the brain significantly. Their estimate? The overweight brain looks 10 years older
compared to the lean brain.
The brain, while an amazingly powerful organ, is not immutable to the aging process. As we age, the brain naturally degenerate. In essence, as we grow older, we lose more white and grey matter, and our brains seemingly “shrink.” Some diseases are known to speed up this process, and obesity is thought to be among this list. However, direct evidence to support this association have been scarce.
"We're living in an aging population, with increasing levels of obesity, so it's essential that we establish how these two factors might interact, since the consequences for health are potentially serious," said Paul Fletcher, professor at the Cambridge Department of Psychiatry, and senior study author.
Now, in a cross-sectional study of 473 people between the 20-87 years old, scientists at the University of Cambridge say the association between obesity and brain shrinkage is clear and very striking.
Using magnetic resonance imaging (MRI), the team collected grey and white matter volumes for all study participants. They then compared the volumes based on the participants who were defined as lean (body mass index 18.5 – 25) to the brain volumes of those who were defined as overweight (BMI 25 – 30) and obese (BMI greater than 30).
Across the study, the team found that the brains of overweight people had less white matter as compared to the brains of lean people. Even more remarkable, the reduction in brain volume for overweight people equaled to that of the brains of lean people who were 10 years older. Thus, it appears that being overweight may age the brain tremendously.
The one silver lining in the study appears to be that the biggest deficit in brain changes happen in middle-aged adults, which suggest that there may time to correct this trajectory, especially for young adults. "The fact that we only saw these differences from middle age onwards raises the possibility that we may be particularly vulnerable at this age. It will also be important to find out whether these changes could be reversible with weight loss, which may well be the case," said Fletcher.
White matter gets its name from the myelinated axons that connect different parts of grey matter to each other. In essence, white matter relays information from the different parts of the brain, and thus, influences how the brain learns and functions. But even with the white matter loss, the team found no changes in an obese person’s cognitive abilities.
"As our brains age, they naturally shrink in size, but it isn't clear why people who are overweight have a greater reduction in the amount of white matter," said Lisa Ronan, first author of the study. "We can only speculate on whether obesity might in some way cause these changes or whether obesity is a consequence of brain changes."
Indeed, it is important to note that this study is an association, pointing out a link between obesity and brain changes. Whether obesity influences the brain to degenerate at a faster rate, or whether the degenerate brain influences obesity.
Additional sources: Unversity of Cambridge