1 of 2 | This image showed increased neuroinflammation (yellow colors) with higher hidden fat in the brain's white matter in the cohort of participants with an average age of 50 years. The green colors are normal white matter. Photo by Dr. Mahsa Dolatshahi/Radiological Society of North America
NEW YORK, Nov. 20 (UPI) -- Having hidden belly fat in midlife is associated with the development of Alzheimer's disease, new research indicates.
The research is being presented this week at the annual meeting of the Radiological Society of North America in Chicago.
Visceral abdominal fat, which has been linked to Alzheimer's, is the fat surrounding the internal organs deep in the belly. Researchers found that this hidden fat is related to changes that occur in the brain up to two decades before the earliest memory loss symptoms of Alzheimer's appear.
It is important to understand the role of this hidden fat plays in contributing to low-grade inflammation and potentially Alzheimer disease, Dr. Mahsa Dolatshahi, the lead author of the study, told UPI via email.
"Hidden fat in the belly is related to the earliest changes of Alzheimer's disease in the brain up to 25 years before symptoms, worse in men than in women," said Dolatshahi, a postdoctoral research associate with Mallinckrodt Institute of Radiology at Washington University School of Medicine in St. Louis.
"This highlights the importance of maintaining a healthy diet and regular physical activity to prevent obesity and the accumulation of hidden belly fat."
More than 6 million Americans are living with Alzheimer's disease, according to the Alzheimer's Association, based in Chicago. By 2050, this number is projected to swell to nearly 13 million. At age 45, the lifetime risk of getting Alzheimer's is 1 in 5 for women and 1 in 10 for men.
For this study, researchers analyzed data from 54 cognitively healthy participants, ranging in age from 40 to 60 years old, with an average body mass index of 32. The participants underwent glucose and insulin measurements, as well as glucose tolerance tests, according to a news release.
The volume of subcutaneous fat -- fat under the skin -- and visceral fat were measured using abdominal MRI. Brain MRI measured the cortical thickness of brain regions that are affected in Alzheimer's disease.
Positron emission tomography, or PET, was used to examine disease pathology in a subset of 32 participants, focusing on amyloid plaques and tau tangles that accumulate in Alzheimer's disease, the release said.
Other research has linked BMI to brain atrophy -- decrease in size or wasting away -- or even a higher dementia risk. However, no previous study has associated a specific type of fat with the actual Alzheimer's disease protein in cognitively normal people as early as midlife, Dolatshahi said.
"This crucial result was discovered as early as midlife, when the disease pathology is at its earliest stages and potential modifications, like weight loss, are more effective and cost less," she said.
Heather Snyder, vice president of medical and scientific relations at the Alzheimer's Association, who was not involved in the study, told UPI in a telephone interview that this research explores "what might be the mechanism -- the biology -- that is tying obesity and BMI to this risk" of memory changes.
"Although it was a relatively small study, this type of work is so important to laying the foundation to better understand the linkages of belly fat and later life risk of cognitive decline," said Snyder, who has a doctorate in molecular biology with a focus on neuroscience.
She added that "there are many studies like this that any of us could be a part of. We should all consider participating in a research study."
Dr. Steven Wengel, a professor and geriatric psychiatry division director at the University of Nebraska Medical Center in Omaha, told UPI in a telephone interview that this "intriguing" and "novel" study fits in with other accumulating evidence about important lifestyle risk factors for Alzheimer's disease.
"We know that body fat can lead to increases in inflammation, and inflammation has been associated with Alzheimer's disease," he said, adding, "It's certainly a reasonable thing to recommend that middle-aged people who are overweight lose weight on general principle, and if it reduces the risk of Alzheimer's disease, it's icing on the cake."
However, Dr. Richard Dupee, chief of geriatrics at Tufts Medical Center in Boston, told UPI in a telephone interview that "there's no relationship between being overweight and developing Alzheimer's. The greatest risk for developing Alzheimer's is age."
He added that this study "might be a good first step," in connecting the dots between excess weight's potential to promote inflammation leading to Alzheimer's. "But we need a much more rigorous study with a lot more patients."
The results of this research should be interpreted with caution because it's a pilot study with few participants, Dr. John A. Batsis, an associate professor in the division of geriatric medicine at the University of North Carolina at Chapel Hill's School of Medicine, told UPI via email.
Even so, "it provides some clues that visceral fat (belly fat) may lead to changes in brain volumes and imaging measures that could be indicative of Alzheimer's pathology," Batsis said.
"Engaging in a healthy lifestyle to reduce this risk and decrease the degree of visceral fat is likely to reduce one's risk. This means controlling other risks that can be modifiable like high blood reassure, diabetes, smoking and high cholesterol," he added.
"The public health concern of Alzheimer's is a real one. While conducting long-term studies is difficult, we need additional data."