Researchers have identified a link between specific types of hidden body fat and the accumulation of abnormal proteins in the brain that signify Alzheimer’s disease. This association appears up to 20 years before the first signs of dementia, according to findings presented at the Radiological Society of North America’s annual meeting. The researchers emphasized that lifestyle changes aimed at reducing this fat could significantly impact the progression of Alzheimer’s disease.
“We investigated Alzheimer’s pathology as early as midlife, in people in their 40s and 50s, when the disease is in its earliest stages. At this stage, interventions such as weight loss and reducing visceral fat are more effective in preventing or delaying disease onset,” said lead author Mahsa Dolatshahi, M.D., M.P.H.
Currently, an estimated 6.9 million Americans aged 65 and older live with Alzheimer’s, a number that could reach 13 million by 2050 without breakthroughs in prevention or treatment. This study focused on modifiable lifestyle factors, such as obesity, body fat distribution, and metabolism, in connection to Alzheimer’s pathology.
The study included 80 cognitively normal midlife individuals with an average age of 49.4 years, 62.5% of whom were women. Around 57.5% of participants were classified as obese, with an average body mass index (BMI) of 32.31. Participants underwent brain PET scans, body MRI, and metabolic assessments, including glucose, insulin, and cholesterol levels. MRI scans of the abdomen measured subcutaneous fat (fat under the skin) and visceral fat (deep fat around organs).
The results revealed that higher levels of visceral fat were strongly correlated with increased levels of amyloid plaques and tau tangles, the hallmark proteins of Alzheimer’s. These findings accounted for 77% of the effect of high BMI on amyloid accumulation, while other fat types showed no significant impact.
The study also found that insulin resistance and lower HDL (“good cholesterol”) were linked to higher amyloid levels. However, participants with higher HDL levels experienced a reduced impact of visceral fat on brain amyloid deposition, highlighting the role of metabolic health in Alzheimer’s risk management.
“This research highlights the need to address metabolic and lipid issues in obesity-related Alzheimer’s risk,” noted senior study author Cyrus A. Raji, M.D., Ph.D.
Unlike prior studies, which broadly associated high BMI with brain cell damage, this study provided a more detailed analysis of fat distribution and metabolic profiles using MRI. This approach allowed researchers to pinpoint the role of visceral fat in Alzheimer’s pathology during midlife, decades before clinical symptoms appear.
Drs. Raji, Dolatshahi, and colleagues also presented related research showing that obesity and visceral fat reduce brain blood flow. The study demonstrated that individuals with high visceral fat exhibited significantly lower whole-brain blood flow compared to those with lower visceral fat. These effects were not observed in groups with high subcutaneous fat, further emphasizing the unique role of visceral fat in brain health.
“This work has profound public health implications, as nearly 75% of Americans are overweight or obese,” Dr. Raji said. “Understanding that visceral fat negatively impacts brain health opens opportunities for lifestyle modifications or targeted therapies to improve cerebral blood flow and reduce Alzheimer’s risk.”
