As per findings to be presented at the upcoming annual conference of the Radiological Society of North America (RSNA), the progression of Alzheimer’s disease is linked to elevated levels of visceral abdominal fat during middle age. Visceral fat refers to the fat surrounding internal organs deep within the abdomen. Research has established a correlation between this hidden belly fat and brain alterations that can manifest up to 15 years before the initial indications of Alzheimer’s disease, such as memory loss. Statistics from the Alzheimer’s Association indicate that approximately 6 million Americans are affected by Alzheimer’s disease. By 2050, this figure is anticipated to surpass 13 million. Alzheimer’s disease impacts about one out of every five women and one out of every ten men at some point in their lives.
The study delved into the correlation between brain MRI volumes, as well as amyloid and tau uptake on positron emission tomography (PET) scans, and body mass index (BMI), obesity, insulin resistance, and abdominal adipose tissue in a middle-aged population with normal cognitive function. Amyloid and tau proteins are believed to disrupt communication between brain cells.
“Although there have been previous studies linking BMI with brain atrophy or a heightened risk of dementia, no prior research has associated a specific type of fat with the actual Alzheimer’s disease protein in cognitively normal individuals,” stated Mahsa Dolatshahi, M.D., M.P.H., a post-doctoral research fellow with Mallinckrodt Institute of Radiology (MIR) at Washington University School of Medicine in St. Louis. “Similar studies have not explored the distinct role of visceral and subcutaneous fat, particularly concerning Alzheimer’s amyloid pathology, as early as midlife.”
The researchers examined data from 54 cognitively healthy individuals, aged 40 to 60 years, with an average BMI of 32. The participants underwent glucose and insulin assessments, as well as glucose tolerance tests. Abdominal MRI was employed to measure the volume of subcutaneous and visceral fat, while brain MRI gauged the cortical thickness of brain regions susceptible to Alzheimer’s disease. Furthermore, PET was utilized to scrutinize disease pathology in a subset of 32 participants, focusing on amyloid plaques and tau tangles that accumulate in Alzheimer’s disease.
The study revealed that a higher ratio of visceral to subcutaneous fat was connected with greater amyloid PET tracer uptake in the precuneus cortex, known to be affected early in Alzheimer’s disease by amyloid pathology. This association was more pronounced in men than in women. Additionally, the researchers found a positive correlation between increased measurements of visceral fat and heightened brain inflammation.
“Several pathways are suggested to play a role,” Dr. Dolatshahi explained. “Inflammatory secretions of visceral fat, as opposed to potentially protective effects of subcutaneous fat, could lead to brain inflammation, a primary mechanism contributing to Alzheimer’s disease.”
Cyrus A. Raji, M.D., Ph.D., the senior author and associate professor of radiology and neurology at MIR, noted that the findings have several crucial implications for early diagnosis and intervention. “This study illuminates a key mechanism by which hidden fat can elevate the risk of Alzheimer’s disease,” he remarked. “It indicates that such brain changes occur as early as age 50, on average–up to 15 years before the initial symptoms of memory loss related to Alzheimer’s appear.”
Dr. Raji emphasized that the results may suggest visceral fat as a target for intervention to minimize the risk of future brain inflammation and dementia. “By moving beyond body mass index and providing better characterization of the anatomical distribution of body fat on MRI, we now possess a distinctly improved understanding of why this factor could heighten the risk for Alzheimer’s disease,” he concluded. (ANI)
