Brains of Overweight People “Ten Years Older” Than Healthy People of Same Age, Study Finds

There were striking differences in white matter volume.

Obesity is linked with a number of health conditions, like diabetes and heart disease, but scientists are just beginning to explore how obesity affects the progression of brain aging.

Studies that directly link obesity to the onset of brain aging are lacking, but new research from a team at the University of Cambridge has found that the brains of obese individuals show white matter volumes similar to those of lean individuals who are ten years older than them.

White matter is critical because it connects areas of the brain and enables information to be communicated between different regions. It’s been known that our brains shrink with age, but white matter’s role in this has yet to be figured out.

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"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," first author Dr. Lisa Ronan, from the Department of Psychiatry at the University of Cambridge, said in a media statement. "We can only speculate on whether obesity might in some way cause these changes or whether obesity is a consequence of brain changes."

Taking a cross-sectional study approach — meaning they looked at data from individuals at one point in time — the team analyzed data from 473 individuals between the ages of 20 and 87, all recruited by the Cambridge Centre for Aging and Neuroscience.

The study participants were divided into two groups: lean and overweight. After observing striking differences in white matter volume in the brains of overweight versus lean individuals, the team calculated how white matter volume related to age across the two groups.

The white matter volume in obese people was significantly lower than that in their healthy counterparts, and the team found that overweight individuals had comparable white matter volume to lean individuals 10 years their senior, implying a sped-up brain age progression of 10 years.

Notably, the researchers only saw these striking differences from middle-age onwards, which suggests that the brain may be particularly vulnerable to aging during this period.

Further, while there was a clear difference in white matter volume between lean and overweight individuals, the researchers found no connection between obesity and an individual’s cognitive abilities after measuring them using a standard test (similar to an IQ test).

"We're living in an ageing 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,” senior author Professor Paul Fletcher, from the Department of Psychiatry, said in the release.

“It will also be important to find out whether these changes could be reversible with weight loss, which may well be the case."

The results are published in the journal Neurobiology of Aging.

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