Radiologists say hidden fat can predict Alzheimer’s 20 years before symptoms arise
Hidden fat can predict an individual’s risk of developing Alzheimer’s disease 20 years before symptoms arise, according to new research being presented this week at RSNA 2024.
Nearly 7 million Americans over 65 live with the disease, a number that could grow to 13 million by 2050. Given this rapid increase, experts say it is essential to develop breakthroughs to address the disease.
Radiology researchers focused their work on modifiable lifestyle factors, such as obesity and body fat distribution, seeking ways to possibly prevent Alzheimer’s. For the study, they imaged 80 cognitively normal individuals (average age of 49.4) using brain positron emission tomography (PET) and body MRI. Subjects also underwent a metabolic assessment and lipid panel.
Higher levels of visceral fat were linked to increased amyloid, an abnormal protein that builds up in the body, accounting for 77% of the effect on high BMI. Meanwhile, other types of fat didn’t explain obesity-related increases in Alzheimer’s pathology.
"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," lead author Mahsa Dolatshahi, MD, with the Mallinckrodt Institute of Radiology at Washington University in St. Louis, Missouri, said in a Dec. 2 announcement from RSNA. "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."
About 57.5% of the participants were obese with an average BMI of 32.31. Thigh imaging was used to measure volume of muscle and fat, while Alzheimer’s pathology was gauged via PET. The study also found that higher insulin resistance and lower HDL (good cholesterol) were associated with high amyloid in the brain. Effects of visceral fat on amyloid pathology were partially reduced in people with higher HDL.
"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," senior study author Cyrus A. Raji, MD, PhD, associate professor of radiology at the Mallinckrodt Institute of Radiology, said in the same announcement.
Previous research has shown the role of high BMI in damaging cells of the brain. However, no study has investigated the differential role of visceral and subcutaneous fat, especially as they relate to Alzheimer’s. The study’s authors also are presenting additional research at RSNA 2024 exploring how obesity and visceral fat reduce blood flow in the brain.
You can find further details about the research in the Monday RSNA announcement here.
Marty Stempniak has covered healthcare since 2012, with his byline appearing in the American Hospital Association's member magazine, Modern Healthcare and McKnight's. Prior to that, he wrote about village government and local business for his hometown newspaper in Oak Park, Illinois. He won a Peter Lisagor and Gold EXCEL awards in 2017 for his coverage of the opioid epidemic.