High body mass index (BMI) in midlife is a significant risk factor for dementia. But comprehensive measures of body fat, such as BMI, may not be the best predictor of cognitive decline after all.
A new study led by researchers at Washington University in St. Louis suggests that the link between body fat and brain health is more subtle.
Their results, which have not yet been published, suggest that deep abdominal fat is associated with markers of Alzheimer’s disease years before cognitive symptoms begin to appear.
A more ubiquitous type of fat called subcutaneous fat failed to explain the association between BMI and dementia markers.
The results of this study were recently presented at the annual meeting of the Radiological Society of North America.
Lead author Martha Drashahi say The “key result” is that a higher proportion of deep visceral fat in people in their 40s or 50s is associated with clumps of amyloid protein in the brain.
These plaques are not necessarily a sign of Alzheimer’s disease, but they can be an early marker of cognitive decline.
“This study shows that in addition to using BMI, MRI can be used to more accurately characterize body fat, and in doing so, explain why obesity may increase the risk of Alzheimer’s disease.” Reveal important insights about say Dorashahi.
“Other studies have linked BMI to brain atrophy and higher risk of dementia, but no previous studies have linked specific types of fat to actual Alzheimer’s disease proteins in cognitively normal people,” Drashahi said. said. explained Prior to the conference.
A growing body of research suggests that some types of fat may be healthier than others, but many studies investigating the link between obesity and dementia lump all types of fat together. Or, it only takes into account subcutaneous fat accumulation, which is easy to measure and causes a huge amount of fat. It makes up the majority of fat in the body.
visceral fat essentially different. It accumulates deep within the body, enveloping organs, as well as affecting cholesterol and insulin production, and can be associated with metabolic problems. Magnetic resonance imaging (MRI) is required to measure visceral fat.
In August, Dorashahi and colleagues published Initial results from a pilot study of 32 adults between the ages of 40 and 60 with normal cognitive abilities. People with more abdominal visceral fat had higher levels of amyloid pathology in the right hemisphere of the brain, indicating thinner cortex in some brain regions associated with Alzheimer’s disease.
The trial was then extended. Researchers say the results of the latest study, which included data from 80 people, show that the ratio of visceral fat to subcutaneous fat in the abdomen is associated with increased amyloid in the brain, which accounts for 77% of the effect of high BMI on amyloid. It states that this shows that the number of Accumulation.
“To our knowledge, our study is the only one to demonstrate these findings in midlife, when participants take decades to develop early symptoms of dementia caused by Alzheimer’s disease. ” said Doratshahi in November.
Interestingly, the research team found that lower levels of high-density lipoprotein (HDL) cholesterol (also known as “good” cholesterol) were associated with higher amyloid levels in the participants’ brains. .
Cholesterol production is influenced by visceral fat, and previous studies have linked cholesterol levels to dementia. In fact, earlier this year, researchers found that too much “good” cholesterol can increase dementia risk in older adults by up to 42 percent.
A higher proportion of visceral fat was also associated with lower insulin levels. A recent study found that people with insulin resistance tend to have faster brain atrophy, and this double whammy significantly increases the risk of developing cognitive problems later in life.
Clearly, the relationship between physical health and the brain is very complex, and more research is needed to understand why people with higher BMI develop Alzheimer’s disease more often.
In the meantime, regular exercise and healthy eating These are two of the best ways a person can protect their brain and body from decline.
The findings were presented at the following conference: 2024 Conference of the Radiological Society of North America.
