Excess body fat linked to shrinking brain and dementia risk

Carrying extra body fat, especially around the middle, may be linked to brain shrinkage, new research suggests.

According to a study published by Neurology, how this extra fat impacts our brain’s functions isn’t yet clear but existing studies have linked brain shrinkage with a higher risk of memory decline and degenerative conditions such as Alzheimer’s disease.

Study author Mark Hamer, of Loughborough University, said: “Our research looked at a large group of people and found obesity, specifically around the middle, may be linked with brain shrinkage.

“We also found links between obesity and shrinkage in specific regions of the brain. This will need further research, but it may be possible that someday regularly measuring BMI and waist-to-hip ratio may help determine brain health.”

Just under 10,000 participants were involved in the study, ranging in age from 40 to 70-years-old. Researchers determined obesity by measuring body mass index (BMI) and waist-to-hip ratio.

Researchers used magnetic resonance imaging to determine brain volumes for white and grey brain matter and volumes in the various regions of the brain.

Grey matter contains most of the brain's nerve cells and includes brain regions involved in self-control, muscle control and sensory perception. White matter contains nerve fibre bundles that connect various regions of the brain.

Taking other factors into account that could produce differences in brain volume – such as age, smoking, and exercise – the study revealed that while a high BMI was linked to slightly lower brain volumes, those with high BMI and waist-to-hip ratios also had lower grey matter brain volumes.

Specifically, researchers found that 1,291 people who had a high BMI and a high waist-to-hip ratio had the lowest average grey matter brain volume of 786 cubic centimetres, compared to 3,025 people of healthy weight who had an average grey matter brain volume of 798 cubic centimetres.

They found no significant differences in white matter brain volume.

Dr James Pickett, head of research at Alzheimer’s Society, added: “We know there’s a link between obesity and dementia, so it’s not hugely surprising to see the results of this study showing obese people had slightly less grey matter, a risk factor for dementia. We don’t know what precisely links obesity, brain health, and risk of dementia, but it is likely that poorer cardiovascular health plays a role.

“It’s predicted that, by 2021, a million of us will have dementia. While we don’t have a cure or any way to slow down the disease, we need to focus on how we can prevent people getting dementia in the first place. While signing up to the marathon is a great start, just going for a brisk walk and cutting down on the sugary snacks will help lower your chances of dementia.”

For more information on the study visit: neurology.org