New research has established a link between a specific type of body fat and the brain proteins that are hallmarks of Alzheimer’s disease.
The type of fat is especially common for people in middle age — and it could signal Alzheimer’s a full two decades sooner than the memory disease’s symptoms.
In a study presented at the annual meeting of the Radiological Society of North America (RSNA), a team from Washington University School of Medicine linked visceral fat — which forms around vital organs like the heart, liver, and stomach — to an increased likelihood of developing dementia within two decades.
“This crucial result was discovered because we investigated Alzheimer’s disease pathology as early as midlife — in the 40s and 50s — when the disease pathology is at its earliest stages,” said lead study author Mahsa Dolatshahi, M.D., M.P.H., postdoctoral research associate at Mallinckrodt Institute of Radiology (MIR) at Washington University School of Medicine in St. Louis, Mo.
“And potential modifications like weight loss and reducing visceral fat are more effective as a means of preventing or delaying the onset of the disease.”
One in every 5 women and 1 out of 10 men will develop Alzheimer’s in their lifetime.
Alzheimer’s is the most common form of dementia, characterized by a decline in memory, thinking and learning. Nearly 7 million Americans have been diagnosed with dementia, but researchers say millions more likely have dementia symptoms but no formal diagnosis.
Dolatshahi and his team focused their study on the association between Alzheimer’s and modifiable factors such as obesity and body fat distribution.
The study included 80 cognitively normal middle-aged subjects, meaning they had no current signs of dementia. Roughly 57.5% of these participants qualified as obese, and the average body mass index (BMI) of all participants was 32.31.
The CDC defines obesity as having a body mass index (BMI) of at least 30, and 20% of Americans meet that criteria.
Participants were subjected to brain positron emission tomography (PET), body MRI, metabolic assessment (glucose and insulin measurements) and a lipid (cholesterol) panel. MRI scans were used on the abdomen to measure the volume of subcutaneous fat, which is found just under the skin, and visceral fat, which is deeper, less visually evident and surrounds the organs.
PET scans were used to measure tracers that bind to brain-clogging protein clumps called amyloid plaques, a telltale biomarker of Alzheimer’s.
The team found that higher visceral fat levels were related to increased amyloid, accounting for 77% of the effect of high BMI on amyloid accumulation.
“Our study showed that higher visceral fat was associated with higher PET levels of the two hallmark pathologic proteins of Alzheimer’s disease — amyloid and tau,” said Dolatshahi.
“To our knowledge, our study is the only one to demonstrate these findings at midlife where our participants are decades out from developing the earliest symptoms of the dementia that results from Alzheimer’s disease.”
Dolatshahi and his team stressed that lifestyle modifications that prevent or reduce visceral fat accumulation could theoretically help prevent or postpone the development of Alzheimer’s disease.
Previous research found that visceral fat may lead to inflammation in the brain, one of the primary mechanisms contributing to Alzheimer’s disease.
“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.
Raji, Dolatshahi and their colleagues will also present a study that shows the relationship between visceral fat, obesity and blood flow in the brain. In the latter study, the team found that those with high visceral fat showed lower whole-brain blood flow.
“This work will have a considerable impact on public health because nearly 3 out of 4 Americans are overweight or obese,” Raji said.
“Knowing that visceral obesity negatively affects the brain opens up the possibility that treatment with lifestyle modifications or appropriate weight-loss drugs could improve cerebral blood flow and potentially lower the burden of and reduce the risk for Alzheimer’s disease.”
Previous research has established that refined carbs and ultra-processed foods (UPFs) are common culprits of belly fat and contributors to cognitive decline. Experts suggest a Mediterranean diet is the best way to combat this fat and potentially prevent dementia. Additional measures to stave off the debilitating disease include regular exercise, abstaining from alcohol and getting quality sleep.
