A higher BMI is associated with decreased white matter in the brai, study reveals

Researchers from the University of Cambridge and Yale University have found a new link between obesity and brain structure.
The study findings, published in the journal Neurobiology of Aging, show that the brains of overweight people age at a faster rate than those of their lean peers.
More specifically, the brains of middle-age people who are obese or overweight appear to have aged an extra ten years compared to lean people.
The brain scanning research conducted by the scientists attributes this stark difference to a greater shrinkage in volume of white matter in the overweight or obese group.
Researchers knew that the volume of white matter in a human brain increases during youth and then decreases with age for both lean and overweight people, but it seems that this process may also depend on a subject’s body mass index (BMI).
The research team tested whether brain volume correlated with BMI and made the discovery by analysing magnetic resonance imaging (MRI) scans from 473 individuals aged between 20 and 87.
Participants were split into two groups based on their BMI with 247 classified as lean (BMI ranging from 18.5 to 24.99 kg/m2) and 227 as overweight or obese (BMI over 30 kg/m2).
Changes with age in global brain volume – and especially white matter volume – was then assessed among participants, taking into account gender and health issues such as high blood pressure and diabetes.
Obese participants over the age of 37 (when changes to brain structure naturally starts to occur) had less white matter volume than lean subjects. Such specific variations in brain matter were also more prevalent around the age of 40 before stabilising.
It is, however, unclear whether an increased BMIBMI alone is driving the effect.
Previous studies have looked at the influence of BMI-linked brain aging and neurodegenerative conditions such as dementia and Alzheimer’s, but this study showed no cognitive differences in overweight or obese participants subjected to IQ tests.
Scientists from Cardiff University’s Brain Research Imaging Centre have suggested that the expression of genes responsible for obesity could also be responsible for white matter shrinkage, which may in turn trigger overeating.
Further research is needed, however, to understand the full impact of obesity on the brain.