Discoveries Revealed: How Excess Midlife Abdominal Fat Is Linked to Alzheimer’s Onset
Recent findings to be presented at the annual meeting of the Radiological Society of North America (RSNA) shed light on the correlation between elevated levels of visceral abdominal fat in middle-aged individuals and the heightened probability of developing Alzheimer’s disease. In-depth research, which involved scrutinizing the brain scans of 54 subjects, has underlined the association between this form of fat and the early occurrence of brain changes and inflammation, emphasizing its prospective relevance in early intervention for Alzheimer’s.
Alarming Rise in Alzheimer’s Cases
According to data provided by the Alzheimer’s Association, over 6 million Americans are currently living with Alzheimer’s disease. This number is anticipated to skyrocket to nearly 13 million by the year 2050. Statistics demonstrate that one in every five women and one in every 10 men are projected to develop Alzheimer’s disease during their lifetime.
Uncovering the Early Indicators of Alzheimer’s
In hopes of identifying the early indicators of Alzheimer’s disease, researchers scrutinized the possible link between the brain MRI volumes, along with amyloid and tau uptake on positron emission tomography (PET) scans, and body mass index (BMI), obesity, insulin resistance, and abdominal adipose (fatty) tissue in individuals of midlife who exhibit normal cognitive functions. Amyloid and tau are proteins believed to impede the communication between brain cells.
This figure shows increased neuroinflammation (yellow colors) associated with higher hidden fat (visceral fat) in the cohort of 54 participants with an average age of 50 years in the brain’s white matter. The green colors are the normal white matter. Credit: RSNA/Mahsa Dolatshahi, M.D., M.P.H.
Novel Insight from a Fat-Related Study on Alzheimer’s Risk
“Despite previous studies linking BMI with brain atrophy or a heightened risk of dementia, no prior study has correlated a precise type of fat with the actual Alzheimer’s disease protein in individuals exhibiting normal cognitive functions,” indicated Mahsa Dolatshahi, M.D., M.P.H., lead author of the study and 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 roles of visceral and subcutaneous fat, particularly in terms of Alzheimer’s amyloid pathology, as early as the middle stages of life.”
Research Methodology and Significant Discoveries
Conducted as a cross-sectional study, the investigation entailed analyzing data from 54 middle-aged, cognitively healthy participants, aged between 40 and 60 years, with an average BMI of 32. The subjects underwent glucose and insulin tests, as well as glucose tolerance assessments. Abdominal MRI was employed to measure the volumes of subcutaneous and visceral fat, while brain MRI gauged the cortical thickness of brain regions affected by Alzheimer’s disease. PET scans were utilized to evaluate disease pathology in a sub-set of 32 participants, focusing on amyloid plaques and tau tangles that accumulate in Alzheimer’s disease.
The findings uncovered that a higher ratio of visceral to subcutaneous fat was associated with elevated amyloid PET tracer uptake in the precuneus cortex, the region that is known to be affected early by amyloid pathology in Alzheimer’s disease. This association exhibited more prominently in men than in women. Moreover, the study revealed a correlation between higher visceral fat measurements and augmented inflammation within the brain.
“Several pathways are suggested to play a role,” according to Dr. Dolatshahi. “Inflammatory secretions of visceral fat, as opposed to potentially protective effects of subcutaneous fat, may lead to inflammation in the brain, which is a major contributing mechanism to Alzheimer’s disease.”
Significance for Early Detection and Medical Intervention
Senior author Cyrus A. Raji, M.D., Ph.D., associate professor of radiology and neurology, and director of neuromagnetic resonance imaging at MIR, highlighted the numerous important implications for earlier diagnosis and intervention provoked by these findings.
“This study illuminates a pivotal mechanism through which hidden fat could elevate the risk of Alzheimer’s disease,” he stated. “It reveals that such brain changes can occur as early as age 50, on average—up to 15 years prior to the initial onset of memory loss symptoms in Alzheimer’s.”
Dr. Raji further added that the results might signify visceral fat as a legitimate target for modifying the risk of future brain inflammation and dementia.
“By going beyond body mass index in providing a comprehensive characterization of body fat distribution on MRI, we now possess a unique understanding of why this factor may heighten the risk for Alzheimer’s disease,” he concluded.
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