(CNN) — Inflammation caused by abdominal fat may be linked to the early stages of Alzheimer’s disease decades before symptoms begin, according to new research.
“We’ve known for a long time that as the size of the abdomen increases, the memory centers in the brain get smaller,” said Alzheimer’s disease researcher Dr. Richard Isaacson, a preventive neurologist at the Institute for Neurodegenerative Diseases. from Florida.
“This study shows a marker of neuroinflammation on brain images that I haven’t seen before,” said Isaacson, who was not involved in the new study. “Brain imaging links abdominal or visceral fat to brain dysfunction through an inflammatory cascade.”
The study found that people in their 40s and 50s with a greater amount of hidden abdominal fat “had a greater amount of an abnormal protein called amyloid in a part of the brain that we know is one of the first places where Alzheimer’s occurs.” said senior author Dr. Cyrus Raji, an associate professor of radiology at Washington University School of Medicine in St. Louis.
Plaques of beta amyloid in the brain are one of the hallmark signs of Alzheimer’s, along with tangles of a protein called tau. Amyloid plaques usually appear first and tau tangles arrive later as the disease progresses.
“There is also a sex difference, where men had a higher relationship between abdominal fat and amyloid than women,” Raji said. “The reason this is important is because men have more visceral fat than women.”
The study also found a link between deep abdominal fat and brain atrophy, or loss of gray matter, in a part of the brain’s memory center called the hippocampus.
“That’s important because brain atrophy is another biomarker of Alzheimer’s disease,” Raji said.
The gray matter of the brain contains most of the brain cells that tell the body what to do. White matter is made up of fibers, normally distributed in bundles called tracts, that form connections between brain cells and the rest of the nervous system.
“We also found that individuals with higher amounts of visceral fat tend to have more inflammation in widespread white matter pathways in the brain,” said lead author Dr. Mahsa Dolatshahi, a postdoctoral researcher at the University’s School of Medicine. from Washington.
Without a functional white matter highway, the brain cannot communicate properly with different parts of the brain and body.
‘Push the envelope’
Published as a pilot study in the journal Aging and Disease in August, Raji and his team originally imaged the brains and bellies of 32 adults between the ages of 40 and 60. The team continued to add participants and is now presenting information on 20 more people — 52 total — at the Radiological Society of North America’s 2023 conference this Monday.
As more people were added to the study, details of how inflammation caused by abdominal fat in the parts of the brain where Alzheimer’s originates were brought into focus. The brain changes they found were modest but significant, Raji said.
“The reason we’ve shown very subtle effects is because we’re looking at middle-aged people (people in their 40s and 50s) whereas previous studies looked at people in their 60s and 70s,” he said. “These are people who, if they develop Alzheimer’s disease, it won’t happen to them for another 20 or 25 years.
“So, we are really pushing the limits of how early we can detect some of the more subtle manifestations of abnormalities that may be related to Alzheimer’s pathology,” Raji added. “By identifying this pathological link with visceral fat, there are ways we can potentially intervene in this population.”
Visceral fat and inflammation
When we think of fat, most of us think of subcutaneous fat, the kind that can be pinched under the skin or along the waist. Subcutaneous fat typically makes up 90% of the body, according to the Cleveland Clinic.
Visceral fat cannot be poked, prodded or pinched. Visceral fat hides behind the abdominal muscles, deep in the abdomen, enveloping vital organs. Both types secrete hormones and other molecules, but experts say visceral fat is more metabolically active and sends signals that can trigger insulin resistance and other health problems.
“Subcutaneous fat is not normally associated with insulin resistance,” Isaacson said. “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 essential for regulating blood sugar levels. The condition often leads to diabetes and a number of other chronic diseases.
“We have hypothesized that inflammation in fat cells leads to insulin resistance, and that is accelerated by visceral fat,” Isaacson said. “Insulin resistance causes inflammation that accelerates the deposition of amyloid, one of the key markers of Alzheimer’s disease. “That is why people with diabetes have twice the risk of suffering from Alzheimer’s disease.”
Expensive MRIs and full-body body 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 measuring tape around your waist, just above your hips.
“For women, 35 inches (89 centimeters) or more means they are at risk for health problems from visceral fat. For men, the number is 40 inches (102 centimeters) or more,” the clinic states on its website.
“Regardless of weight, people should find out if they have hidden visceral fat,” Raji said. “It can be completely missed if you use body mass index (BMI) or weight on the scale.”
This is because even thin people can have excess visceral fat. Called “skinny fat” or “TOFI” (thin on the outside, fat on the inside), it can occur when a person exercises but has a poor diet, and in certain ethnic groups. Asians, for example, have more visceral fat than blacks, whites or Hispanics.
Visceral fat is “easier to lose”
There’s good news: Visceral fat responds well to diet and exercise, Raji said. “It is easier to lose visceral fat with diet and exercise than it is to lose subcutaneous fat because visceral fat is more easily metabolized and burned.”
“There are several things that can target body fat, both from an exercise and nutrition perspective,” Isaacson said.
“Eat a healthy diet and exercise regularly, which should include muscle strength training a few times a week, along with less intense fat-burning cardio exercises for 45 to 60 minutes, several times a week,” he said.
More tips: Eliminate or reduce ultra-processed foods, reduce portion sizes, replace sugary drinks with water, limit processed meats, and reduce high-fat meat and dairy products, such as cheese and butter, which are filling of saturated fat, other experts suggest.
Watch your alcohol consumption, too: It’s not just beer that causes a “beer belly,” according to the Mayo Clinic. Drinking alcohol of any kind will enlarge your waist.
Take care of your sleep too. Millions of Americans are sleep deprived daily, but studies have found that people who sleep less than six hours a day have higher levels of amyloid in the brain.