Scientists pinpoint the body type which can protect you against brain ageing linked to dementia
Researchers may be on the edge of a medical breakthrough, after finding that people with more muscle mass, but less hidden fat have healthier, younger brains.
Experts have long warned that obesity increases the risk of a number of serious health conditions including high blood pressure, diabetes and even cancer, with studies showing it may also increase the risk of dementia.
But now, US researchers have found that a specific body profile—namely a higher muscle mass combined with a lower visceral fat to muscle ratio—can help protect the brain against diseases such as Alzheimer’s.
Dr Cyrus Raji, an associate professor in radiology and neurology at Washington University School of Medicine and study lead author, said: ‘Healthier bodies with more muscle mass and less hidden belly fat are more likely to have healthier, youthful brains.
‘Better brain health, in turn, lowers the risk for future brain diseases such as Alzheimer’s.’
Unlike fat that can be seen around the hips, thighs and abdomen, visceral fat is found beneath the abdominal wall, surrounding the internal organs—meaning many people who appear slim may still be carrying harmful amounts.
Muscle mass, as tracked by Magnetic Resonance Imaging (MRI), but also much easier to see, can be a marker for various interventions to reduce frailty and boost brain health.
‘While it is commonly known that chronological age translates to loss of muscle mass and increased hidden belly fat, this work shows that these health measures relate to brain ageing itself,’ Dr Raji added.
Experts have long warned that obesity increases the risk of serious health conditions, such as high blood pressure, as well as cancers, with studies showing it may induce cognitive decline
‘It shows muscle and fat mass quantified in the body are key reflectors of brain health, as tracked with brain ageing.’
Results, published by the Radiology Society of North America, have so far linked higher visceral fat to muscle ratio with an older brain age, but research is ongoing to confirm results.
In the study, researchers examined the MRIs of 1,164 healthy individuals, aged around 55-years old, across four different sites.
They combined whole body MRIs with T1-weighted sequences, in which fat appears bright whilst water appears dark, allowing for optimal imaging of muscle, fat and brain tissue.
Interestingly, the researchers found that a higher hidden belly fat to muscle ratio was associated with an older brain age, while fat under the skin showed no such link.
As Dr Raji explained: ‘The participants with more muscle tended to have younger-looking brains, while those with more hidden belly fat relative to their muscle had older-looking brains.
‘The fat just under the skin wasn’t related to brain ageing. In short, more muscle and a lower visceral fat to muscle ratio were linked to a younger brain.’
Whilst the researchers noted that this work demonstrates how closely body and brain health are linked—with building muscle and reducing hidden fat both actionable goals through lifestyle changes—the study is ongoing.
Researchers calculated an estimation of brain age from MRI brain scans which they then compared with muscle mass
And given that blockbuster weight loss jabs like Ozempic and Mounjaro, have been shown to target muscle mass as well as fat, Dr Raji hopes their findings will inform the design of future weight loss treatments that target hidden fat,
He said: ‘Losing fat—especially visceral fat—while preserving muscle volume would have the best benefit on brain aging and brain health based on insights from our work.
‘Thus, our study can inform future treatments by promoting research that quantifies MRI of body fat, muscle and brain age, which can help determine the optimal dosing regimes for GLP-1s to achieve the best outcomes in body and brain health.’
It comes as a landmark study last year suggested almost half of Alzheimer’s cases—the most common form of dementia—could be prevented by tacking 14 lifestyle factors from childhood.
World-leading experts found two new risk factors—high cholesterol and suffering vision loss—were, combined, behind almost one in ten dementia cases globally.
And whilst it is completely normal to have some visceral fat, having too much has been shown to drive cholesterol, which in turn increases the risk of dementia.
Cholesterol is a fatty wax-like substance found in every cell in the body, helping keep bones and muscles healthy, but too much low density lipoproteins (LDL), or ‘bad cholesterol’, can lead to a build up of the fatty substance which clogs the arteries.
This can increase the risk of stroke and cause more toxic proteins, such as amyloid, to build up in the brain.
Significant clumps of amyloid and tau proteins can form plaques and tangle — and this is thought to be behind Alzheimer’s symptoms. Pictured, an Alzheimer’s affected brain, with abnormal levels of amyloid protein clumping together
Significant clumps of this protein, as well as another called tau, can increase the risk of plaques and tangles forming in the brain and this is thought to be behind the symptoms of Alzheimer’s.
Alzheimer’s Disease is thought to affect 982,000 people in the UK.
Memory problems, thinking and reasoning difficulties and language problems are common early symptoms of the condition, which then worsen over time.
Alzheimer’s Research UK analysis found 74,261 people died from dementia in 2022 compared with 69,178 a year earlier, making it the country’s biggest killer.
However, Alzheimer’s disease is on the rise globally; figures from Frontiers revealed that from 1990 to 2019, new cases of Alzheimer’s and other dementias globally rose by approximately 148 per cent, and total cases increased by around 161 per cent.
