Hidden Fat Can Predict Alzheimer’s Up to 20 Years Before Symptoms Appear

Researchers have linked a specific type of body fat to the buildup of abnormal brain proteins—hallmarks of Alzheimer’s disease—up to 20 years before the earliest symptoms of dementia appear. This finding, presented at the annual meeting of the Radiological Society of North America (RSNA), highlights the potential for lifestyle changes targeting visceral fat to influence Alzheimer’s development.

“This discovery is significant because we focused on Alzheimer’s pathology in midlife, during the 40s and 50s, when interventions like weight loss and reducing visceral fat could be more effective in preventing or delaying the disease,” explained lead author Dr. Mahsa Dolatshahi, a postdoctoral research associate at Mallinckrodt Institute of Radiology (MIR), Washington University.

Alzheimer’s currently affects an estimated 6.9 million Americans aged 65 and older, with numbers projected to rise to 13 million by 2050 without medical breakthroughs. The study focused on how modifiable lifestyle factors, including obesity, fat distribution, and metabolism, relate to Alzheimer’s pathology.

Eighty cognitively normal middle-aged participants (average age: 49.4 years; 62.5% female) underwent brain PET scans, body MRI, and metabolic assessments. On average, participants had a BMI of 32.31, with 57.5% classified as obese. MRI scans measured subcutaneous fat (under the skin) and visceral fat (around organs), while PET scans detected amyloid plaques and tau tangles, key Alzheimer’s markers.

“We analyzed BMI, visceral fat, subcutaneous fat, liver fat, thigh fat and muscle, insulin resistance, and HDL cholesterol in relation to amyloid and tau deposition,” said Dr. Dolatshahi.

Visceral Fat Strongly Linked to Amyloid Accumulation, Mitigated by Higher HDL Levels

The results showed that higher visceral fat correlated with increased amyloid, explaining 77% of the effect of high BMI on amyloid accumulation. No other fat types showed a similar link. Additionally, higher insulin resistance and lower HDL levels were associated with elevated amyloid levels. Notably, participants with higher HDL showed a reduced impact of visceral fat on amyloid pathology.

“Our findings reveal that visceral fat plays a critical role in Alzheimer’s-related brain changes decades before symptoms arise,” Dr. Dolatshahi said. “This emphasizes the need to target metabolic and lipid issues linked to obesity in managing Alzheimer’s risk.”

The team also presented another study at RSNA 2024, showing that obesity and visceral fat reduce brain blood flow. Using brain and abdominal MRIs, they found that individuals with high visceral fat had lower whole-brain blood flow compared to those with low visceral fat, whereas subcutaneous fat had no significant impact.

“This research could have profound public health implications,” said senior author Dr. Cyrus Raji. “With nearly 75% of Americans classified as overweight or obese, addressing visceral obesity through lifestyle changes or weight-loss medications may improve brain health, increase blood flow, and reduce Alzheimer’s risk.”

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