Excess fat has been linked to many health conditions, even some that impact the brain.
In the latest Alzheimer’s research, hidden fat in certain parts of the body was shown to be an early warning sign of the most common dementia — as much as 20 years prior to symptoms emerging.
The study findings were presented this week at the annual Radiological Society of North America (RSNA) meeting in Chicago.
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"Among different body compartments, higher visceral or hidden belly fat is the most important predictor of whole-brain amyloid and early tau protein accumulation," lead study author Mahsa Dolatshahi, M.D., post-doctoral research associate at Mallinckrodt Institute of Radiology (MIR) at the Washington University School of Medicine, told Fox News Digital.
The researchers studied different kinds of body tissues — including subcutaneous fat, liver fat and thigh fat — but visceral fat was the "most powerful predictor of the obesity-related Alzheimer's disease (AD) pathologies," Dolatshahi noted.
"The other types of fat did not show any associations with AD pathologies."
In the study, researchers assessed 80 middle-aged adults (averaging 49 years old) who did not have any cognitive impairment, according to a press release.
Just over half of the people were categorized as obese.
The average body mass index (BMI) was 32.31, with anything over 30 falling into the obesity category.
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The researchers assessed the potential connection between signs of Alzheimer’s disease and controllable lifestyle factors, including obesity, metabolic health and BMI.
Tests included brain scans, body MRIs, cholesterol panels, and measurements of blood glucose and insulin levels.
Beyond just measuring BMI, the study used MRI technology to look closer at body fat and better determine its relationship to Alzheimer’s, the release noted.
"We investigated the association of BMI, visceral fat, subcutaneous fat, liver fat fraction, thigh fat and muscle, as well as insulin resistance and HDL (good cholesterol), with amyloid and tau deposition in Alzheimer's disease," said Dolatshahi.
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An additional finding was that higher insulin resistance and lower HDL were associated with high amyloid in the brain, which is a hallmark of Alzheimer’s.
"A key implication of our work is that managing Alzheimer's risk in obesity will need to involve targeting the related metabolic and lipid issues that often arise with higher body fat," said senior study author Cyrus A. Raji, M.D., Ph.D., associate professor of radiology at MIR, in the release.
In a separate study that is also being presented this week, the same research team investigated how obesity and belly fat can impair blood flow to the brain.
Three out of four Americans are overweight or obese, the researchers noted.
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Meanwhile, approximately 6.9 million Americans, aged 65 and older, have been diagnosed with Alzheimer's disease, a number that has been predicted to reach 13 million by 2050.
Dr. Earnest Lee Murray, a board-certified neurologist at Jackson-Madison County General Hospital in Jackson, Tennessee, was not involved in the study but commented on the results.
"We have known for some time the dangers of visceral fat on various organs of the body, likely from its facilitation of inflammatory changes — and it’s no different in the brain," he told Fox News Digital.
What stuck out most to Murray was how early in life the changes are noted in the brain.
"The good news is these risk factors can be lowered with a healthy lifestyle and routine exercise," he said.
The popularity of GLP-1 medications for diabetes and obesity "will most certainly be studied" in this context as well, Murray added.
"This study also shows the importance of physicians and insurance companies focusing on prevention and the long-term benefits of modifying risk factors at an early age, as opposed to waiting for patients to develop symptoms."
The study did have some limitations, the researchers acknowledged.
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"One is the cross-sectional design of the study, which does not allow us to understand whether the individuals with excess visceral fat and amyloid and tau pathologies will develop cognitive impairment and symptomatic AD," Dolatshahi told Fox News Digital.
"Also, the sample size for this study is limited to 80 individuals, and we need more studies to understand the role of different kinds of body adiposity in Alzheimer's disease using PET scans."
