A study published this week has suggested that dietary changes made in midlife could “prevent or delay” the onset of Alzheimer’s disease. The research has identified a specific type of body fat linked to abnormal proteins in the brain, which are considered “hallmarks” of the disease.
These proteins can signal Alzheimer’s up to two decades before the earliest dementia symptoms manifest, according to the study presented at the annual meeting of the Radiological Society of North America (RSNA) on Monday. The researchers behind the study believe that lifestyle modifications reducing this particular fat – known as visceral fat – could impact the development of Alzheimer’s.
Lead author of the study, Mahsa Dolatshahi, a post-doctoral research associate at Mallinckrodt Institute of Radiology (MIR) at Washington University School of Medicine in St Louis, Missouri, said: “This crucial result was discovered because we investigated Alzheimer’s disease pathology as early as midlife – in the 40s and 50s – when the disease pathology is at its earliest stages and potential modifications like weight loss and reducing visceral fat are more effective as a means of preventing or delaying the onset of the disease.”
The study focused on the connection between modifiable lifestyle-related factors such as obesity, body fat distribution, metabolic aspects, and Alzheimer’s disease pathology.
A total of 80 individuals, deemed “cognitively normal”, participated in the study. They had an average age of 49.4 and 62.5% were female.
In a significant study involving 80 participants, over half (57.5%) were found to be obese, boasting an average BMI of 32.31. The individuals in question underwent several tests comprising MRI scans, along with checks for their glucose and insulin levels, and a cholesterol examination.
The MRI was utilised to gauge the volume of two distinct types of fat – visceral fat, which lurks deep around the internal organs, and subcutaneous fat, found just beneath the skin’s surface.
Dr Dolatshahi, who is part of the esteemed Raji Lab at MIR’s Neuroimaging Labs Research Center, explained: “We investigated the association of BMI, visceral fat, subcutaneous fat, liver fat fraction, thigh fat and muscle, as well as insulin resistance and HDL (good cholesterol), with amyloid and tau deposition in Alzheimer’s disease.”
Part of the study entailed using thigh muscle scans to determine the quantity of muscle and fat present. To detect Alzheimer’s pathology, PET scans were employed with specialised tracers that stick to amyloid plaques and tau tangles – hallmarks of the disease accumulating in afflicted brains.
It was discovered in the research findings that a higher presence of visceral fat corresponded with an uptick in amyloid, which explained a notable 77% of the relationship between elevated BMI and the gathering of amyloid. In contrast, none of the other fat types were implicated in the rise of Alzheimer’s related issues due to obesity.
Dr Dolatshahi revealed: “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.”
Senior study author Cyrus A. Raji, associate professor of radiology at MIR, commented: “A key implication of our work is that managing Alzheimer’s risk in obesity will need to involve targeting the related metabolic and lipid issues that often arise with higher body fat.”
Dr Dolatshahi further noted that while previous studies have highlighted the impact of high BMI on brain cell damage, none have delved into the specific roles of visceral and subcutaneous fat or metabolic profile in relation to Alzheimer’s amyloid pathology at such an early stage as midlife.
“This study goes beyond using BMI to characterize body fat more accurately with MRI and, in so doing, reveals key insights about why obesity can increase risk for Alzheimer’s disease,” Dr Dolatshahi concluded.