Dementia warning as middle aged men with spare tire bellies may be at higher risk of Alzheimer's disease

For the study, scientists at Rutgers University analysed over 200 healthy volunteers using MRI scans.

They discovered that higher levels of fat lurking near the liver, pancreas and bellies correlated with shrunken brain volumes and lower scores on cognitive tests like memory and processing speed.

It comes after research published last year showed that visceral fat, which accumulates around the organs of even people at healthy BMIs, is associated with changes in the brain.

The dangers associated with having visceral fat are well known. It's proximity to internal organs hikes the risk of metabolic syndrome, a collection of disorders that include high blood pressure, obesity, high cholesterol and insulin resistance.

And visceral fat can contribute to a beer belly, also known as subcutaneous fat. However, researchers have long known the former poses a far greater risk than the latter.

"Our findings indicate stronger correlations compared to the relationships between BMI and cognition, suggesting that abdominal fat depots, rather than BMI, is a risk factor for lower cognitive functioning and higher dementia risk,” explains lead author Sapir Golan Shekhtman, a PhD student at Sheba Medical Center in Israel.

Autopsies consistently find obese people carry more Alzheimer’s-linked protein clumps like amyloid-beta plaques compared to lean individuals upon death.

The Rutgers team decided to investigate this link further, by looking into middle aged men who are genetically predisposed towards Alzheimer's.

Of the 204 volunteers with an average age of about 60, each had at least one parent diagnosed with sporadic Alzheimer’s dementia. About 60 percent were female.

One showed cognitive impairments during testing themselves, but researchers could examine early subtle impacts fat deposits and sex differences might have on resilient brain networks.

MRI scans quantified liver, pancreas and abdominal fat around each participant’s organs.

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Compared to recordings of youthful brains as benchmarks, male volunteers on average showed significantly less gray matter volume in important memory regions like the hippocampus by middle age. Grey matter in females declined less drastically.

Curiously, while both men and women carried comparable amounts of hidden belly fat, only overweight males exhibited shrinking regions of the brain responsible for attention, learning and emotion regulation.

More abdominal fat buildup in men also meant scoring worse on cognitive tests and surveys of executive functioning essential for daily life activities like paying bills or medications management. No such brain behaviour patterns emerged among women.

Further research is needed to understand the underlying mechanisms.

In the meantime, it's important to keep belly fat at bay and exercise is a great place to start.

Harvard Health explains: "Even if you don't lose weight, you lose visceral belly fat and gain muscle mass. Engage in at least 30 minutes of moderate-intensity activity most days, such as brisk walking or bicycling at a casual pace."