Too Much Belly Fat Linked to Dementia
Study Shows Deep Belly Fat May Be Linked to Shrinkage in Brain Volume
May 20, 2010 -- Excess belly fat may make your brain shrink and boost your risk of dementia later, according to a new study.
The real culprit is deep belly fat, also known as visceral fat, says study researcher Sudha Seshadri, MD, an associate professor of neurology at the Boston University School of Medicine.
''The greater the amount of visceral fat, the smaller the brain," she tells WebMD. While she didn't follow the participants to see if they developed dementia, she says that ''smaller brain volume is associated with poor cognitive function on testing and a greater risk of dementia on follow-up.''
The study is published online in the Annals of Neurology.
About 5.3 million Americans have Alzheimer's disease, according to the Alzheimer's Association. It's the most common form of dementia -- the loss of cognitive ability affecting memory, language, thinking, and judgment.
Much previous research has looked at the dangers of belly fat, with experts warning it boosts the risk of heart attack and heart disease. More recently, researchers have found the link with brain health.
Before her study, Seshadri says, "It was known that midlife obesity, from age 55 on, was a risk factor for dementia. It's not just your BMI but the central obesity which seems to add increased risk over just the BMI [if it's in the obese range, 30 and higher.]"
While previous research has linked excess visceral belly fat with dementia, Seshadri says many studies have included fewer than 300 participants. One exception is a study published in 2008, involving more than 6,500 participants, finding the more belly fat, the greater the risk of being diagnosed with Alzheimer's or other dementias later in life. Those with the biggest bellies had nearly a three times greater risk of dementia compared to the people with the smallest bellies.
Measuring Belly Fat
Seshadri and her team performed CT scans of the abdomen and MRI scans of the brain of 733 men and women who were participants in the Framingham Heart Study Offspring Cohort. On average, they were age 60; about 70% of participants were women.
Seshadri's team looked at the potential associations of body mass index, waist circumference, waist-to-hip ratio, and the CT measure of abdominal fat with the total brain volume.
The CT measured both visceral or deep belly fat and subcutaneous fat -- the fat that lies right below the skin.
While Seshadri can't quantify the risk of having a high amount of belly fat with a specific brain shrinkage, she says the results she found are linear: the more belly fat, the lower the brain volume.
The deep fat is the culprit, she says. "We found that subcutaneous was not [significantly] associated with any adverse effect on the brain volume, whereas visceral fat was clearly associated with smaller brain volume."