Greater amounts of visceral fat in middle age are linked to the development of Alzheimer’s disease, according to research to be presented at the annual meeting of the Radiological Society of North America.

Visceral fat is the fat that surrounds the internal organs deep in the abdomen. According to the Alzheimer’s Association of America, there are more than six million Americans living with Alzheimer’s disease. By 2050 this number is expected to increase to nearly 13 million. One in five women and one in ten men will develop the disease during their lifetime.

The researchers found that this “hidden” abdominal fat is associated with changes in the brain up to 15 years before the first symptoms appear memory loss of Alzheimer’s disease.

To try to identify risk factors for the disease earlier, the researchers evaluated the correlation between brain volume on MRI and uptake of amyloid and Tau protein (proteins thought to interfere with communication between brain cells) on positron emission tomography scans ( PET) with body mass index, obesity, insulin resistance and abdominal adipose tissue in a normal middle-aged population.

They analyzed data from 54 cognitively healthy participants, ages 40 to 60, with an average body mass index of 32. Participants underwent glucose and insulin measurements, as well as a glucose tolerance test. Subcutaneous fat and visceral fat volume were measured by abdominal MRI. Magnetic resonance imaging of the brain measured the cortical thickness of brain regions affected by Alzheimer’s disease.

The researchers found that higher visceral fat readings are associated with an increased burden of inflammation in the brain. Also, a higher ratio of visceral to subcutaneous fat was associated with higher amyloid uptake in the presphenoid cortex, the region affected early in Alzheimer’s disease.

Associate Professor of Radiology and Neurology at Washington University in St. Louis and one of the study’s lead authors, Cyrus Raji, notes that the findings contribute to early diagnosis and intervention. “This study highlights a key mechanism by which hidden fat may increase the risk of Alzheimer’s disease. It shows that such changes in the brain occur as early as the age of 50, on average, up to 15 years before the first symptoms of memory loss of the disease appear,” he explains. The research results, he adds, may point to visceral fat as a therapeutic target for modifying the risk of future brain inflammation and dementia.