Researchers here report that the amount of visceral fat carried by an individual correlates with the burden of Alzheimer’s-related pathological protein aggregation in the brains of people in middle age prior to the development of any neurodegenerative condition. It is at this point well known that visceral fat specifically is metabolically active, promoting chronic inflammation and in at least some aspects literally accelerating aging. The study population was largely obese, so this study tells us little regarding whether this relationship extends into much lesser degrees of being overweight. Past data has suggested that any amount of excess visceral fat tissue produces dysfunction, scaling up with the size of the excess, however.
Researchers focused on the link between modifiable lifestyle-related factors, such as obesity, body fat distribution and metabolic aspects, and Alzheimer’s disease pathology. A total of 80 cognitively normal midlife individuals (average age: 49.4 years) were included in the study. Approximately 57.5% of participants were obese, and the average body mass index (BMI) of the participants was 32.31. The participants underwent brain positron emission tomography (PET), body MRI, and metabolic assessment (glucose and insulin measurements), as well as a lipid (cholesterol) panel. MRI scans of the abdomen were performed to measure the volume of the subcutaneous fat (the fat under skin) and visceral fat (deep hidden fat surrounding the organs). Thigh muscle scans were used to measure volume of muscle and fat. Alzheimer’s disease pathology was measured using PET scans with tracers that bind to amyloid plaques and tau tangles that accumulate in the brains of people with Alzheimer’s disease.
Our study showed that higher visceral fat was associated with higher PET levels of the two hallmark pathologic proteins of Alzheimer’s disease – amyloid and tau. To our knowledge, our study is the only one to demonstrate these findings at midlife where our participants are decades out from developing the earliest symptoms of the dementia that results from Alzheimer’s disease.” The study also showed that higher insulin resistance and lower HDL were associated with high amyloid in the brain. The effects of visceral fat on amyloid pathology were partially reduced in people with higher HDL.
