Carrying extra weight in midlife has long been linked to an increased risk of dementia, but a new study suggests not all fat is created equal when it comes to brain health. Researchers from Washington University in St. Louis have found that deep visceral fat, rather than overall body mass or subcutaneous fat, may be a critical factor in the development of Alzheimer’s-related brain changes, even decades before cognitive symptoms emerge.
Visceral Fat and Brain Health
Presented at the annual meeting of the Radiological Society of North America, the study revealed that visceral fat—stored deep in the abdomen around internal organs—is strongly associated with the buildup of amyloid protein in the brain. These amyloid plaques are a hallmark of Alzheimer’s disease, although their presence doesn’t always result in the condition.
Lead researcher Mahsa Dolatshahi emphasized the significance of this finding: “Higher levels of visceral fat in individuals during their 40s and 50s are linked to amyloid protein deposits in the brain. This connection sheds new light on why obesity in midlife is a risk factor for Alzheimer’s.”
While subcutaneous fat, which sits just beneath the skin, was not found to be linked to amyloid accumulation, visceral fat showed a direct association with both amyloid buildup and a thinning of the brain’s cortex in regions associated with Alzheimer’s.
New Insights Into Fat Types and Alzheimer’s Risk
Visceral fat is distinct from subcutaneous fat in its effects on the body. It impacts cholesterol production, insulin regulation, and metabolic health. The study used MRI scans to measure visceral fat, offering a more precise analysis than traditional metrics like BMI.
An earlier pilot study involving 32 adults with normal cognition showed similar findings. The extended research, now including 80 participants aged 40 to 60, demonstrated that the ratio of visceral to subcutaneous fat in the abdomen explains 77% of the relationship between high BMI and amyloid protein accumulation in the brain.
This study is unique in examining midlife participants—decades before Alzheimer’s symptoms typically appear.
Cholesterol and Insulin Connections
The research also revealed that participants with lower levels of HDL cholesterol (the “good” cholesterol) had higher levels of amyloid plaques in their brains. Cholesterol levels, influenced by visceral fat, have been linked to dementia risk in past studies.
Additionally, lower insulin levels were observed in participants with more visceral fat. Insulin resistance, which is often associated with high visceral fat, has been tied to accelerated brain shrinkage and a greater likelihood of developing cognitive decline.
Complex Interplay of Body and Brain Health
The findings highlight how the health of the body and brain are deeply intertwined. While much remains unknown about the precise mechanisms linking visceral fat to Alzheimer’s, these results reinforce the importance of managing weight and metabolic health in midlife to protect against future cognitive decline.
Regular exercise and a balanced diet are effective ways to reduce visceral fat, improve cholesterol levels, and maintain insulin sensitivity—factors that could collectively reduce the risk of dementia.
As Dolatshahi notes, “Our study underscores the need for more research into the role of visceral fat and its effects on the brain, especially in midlife, when interventions could potentially have the greatest impact on long-term brain health.”
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