Link found between belly fat and brain inflammation

The danger manifests itself differently in men and women

Inflammation due to belly fat may be linked to the early stages of Alzheimer's disease, decades before symptoms appear, a new study has found.

Photo: Global Look Press

“We have known for a long time that as belly size increases, the memory centers in the brain become smaller”, — CNN quotes Alzheimer's disease researcher Dr. Richard Isaacson, a preventive neurologist at the Florida Institute of Neurodegenerative Diseases.

«This study shows a brain imaging marker of neuroinflammation that I haven't seen before,» says Isaacson, who was not involved in the new study. – Brain imaging links abdominal fat, or visceral fat, to brain dysfunction through an inflammatory cascade.

The study found that people aged 40 to 50 with more hidden belly fat «had more of an abnormal protein called amyloid in a part of the brain that we know is one of the earliest sites of Alzheimer's disease.» ;, said senior author Dr. Cyrus Raji, assistant professor of radiology. at Washington University School of Medicine in St. Louis.

Beta-amyloid plaques in the brain are one of the hallmarks of Alzheimer's disease, along with tangles of a protein called tau. Amyloid plaques usually appear first, and tau tangles appear later as the disease progresses, CNN explains.

“There was also a gender difference, where men had a higher relationship between belly fat and amyloid than women,” Raji says. – The reason this is important is that men have more visceral fat than women.

The study also found a link between deep belly fat deposits and brain atrophy, or gray matter depletion, in part of the brain's memory center called the hippocampus.

«This is important because brain atrophy is another biomarker of Alzheimer's disease,» Raji explains.

The brain's gray matter contains most of the brain cells that tell the body what to do. White matter is made up of fibers, usually distributed in bundles called tracts, which form connections between brain cells and the rest of the nervous system.

“We also found that people with more visceral fat tended to have more inflammation in widespread areas of white matter in the brain,” said lead author Dr. Mahsa Dolatshahi, a postdoctoral fellow at the University of Washington School of Medicine.

< p>Without a functional white matter backbone, the brain cannot communicate adequately with different parts of the brain and body.

Raji and his team initially photographed the brains and stomachs of 32 adults between the ages of 40 and 60, CNN reported. The team continued to add members and is now reporting an additional 20 people — only 52 — at the 2023 Radiological Society of North America meeting on Monday.

As more people joined the study, details of how inflammation from belly fat affects parts of the brain came into focus. Where does Alzheimer's disease occur? The brain changes they found were modest but significant, Raja said.

“The reason we showed very subtle effects is because we are looking at middle-aged people— people aged 40 to 50 years, — while earlier studies looked at people in their 60s and 70s, he said. – These are people who, even if they develop Alzheimer's disease, will not do so for another 20 or 25 years.»

«So we're really pushing the envelope on how early we can detect some of the most subtle manifestations of abnormalities that may be associated with Alzheimer's pathology,» Raji added. – By identifying this pathological association with visceral fat, we can potentially intervene in this population.

When we think of fat, most of us think of subcutaneous fat, the type of fat that you can compress under the skin or along a line waist, notes CNN. According to the Cleveland Clinic, subcutaneous fat typically makes up 90% of the body.

Visceral fat should not be touched, poked or pinched. Visceral fat hides behind the abdominal muscles, deep in the abdomen, enveloping the vital organs. Both types release hormones and other molecules, but experts say visceral fat is more metabolically active, sending signals that can trigger insulin resistance and other health problems.

“Subcutaneous fat generally does not associated with insulin resistance, emphasizes Dr. Isaacson. – However, the higher the level of visceral fat, the more insulin resistance a person has, which causes inflammation in the body and brain.

Insulin resistance occurs when the body's cells do not respond well to insulin, a hormone needed to regulate blood sugar levels. This condition often leads to diabetes and many other chronic diseases.

“We hypothesized that inflammation in fat cells leads to insulin resistance, and this is accelerated by visceral fat,” Isaacson says. – Insulin resistance then causes inflammation, which accelerates the deposition of amyloid, one of the key markers of Alzheimer's disease. That's why people with diabetes are twice as likely to develop Alzheimer's.

Expensive full-body magnetic resonance imaging scans are the most accurate way to measure visceral fat, but many use estimates based on waist circumference or waist size in proportion to height. To measure your waist, the Cleveland Clinic recommends wrapping a flexible tape measure around your waist, just above your hips. “For women, being 35 inches (89 centimeters) or taller means you are at risk for health problems related to visceral fat. For men, that number is 40 inches (102 centimeters) or more,” the clinic says on its website.

“Regardless of weight, people should find out if they have hidden visceral fat,” said Raji. “This can be completely missed by using body mass index (BMI) or weight on a scale.”

According to Raja, the good news is that visceral fat responds well to diet and exercise. “It is easier to get rid of visceral fat through diet and exercise than to get rid of subcutaneous fat because visceral fat is more easily absorbed and burned.

According to Dr. Isaacson, there are many factors that can affect body fat, both from an exercise and nutrition perspective. “Eat a healthy diet and exercise regularly, which should include muscle strength training several times a week, as well as less intense fat-burning cardio for 45 to 60 minutes several times a week,” he said.

Additional tips from CNN: Eliminate or reduce ultra-processed foods, reduce portion sizes, replace sugary drinks with water, limit processed meats and reduce consumption of meat and high-fat dairy products such as cheese and butter that contain saturated fat, other experts advise. It's also worth watching your alcohol consumption: according to the Mayo Clinic, it's not just beer that leads to a «beer belly.» Drinking alcohol of any kind will increase your waistline. It is worth paying attention to sleep. Millions of Americans, CNN notes, suffer from sleep deprivation every day, but studies have shown that people who sleep less than six hours a night have higher levels of amyloid in the brain.