People who have big bellies in their 40s are much more likely to get Alzheimer's disease and other forms of dementia in their 70s, research shows.
FRESNO, Calif. — People who have big bellies in their 40s are much more likely to get Alzheimer’s disease and other forms of dementia in their 70s, according to new research that links the middle-age spread to fading minds for the first time.
The study of more than 6,000 people found the more fat they had in their guts in their early- to mid-40s, the greater their chances of becoming forgetful or confused or showing other signs of senility as they aged. Those who had the most impressive midsections faced more than twice the risk of the leanest.
The study also suggests that abdominal fat is a bigger risk factor for dementia than family history is.
Scientists have known a large belly is associated with an increased risk for diabetes, stroke and heart disease, but this is the first study to show a connection between midlife abdominal fat and dementia.
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“A large belly independent of total weight is a potent predictor of dementia,” said Rachel Whitmer, a scientist at the Kaiser Permanente Division of Research in Oakland, Calif., who led the study. “People need to be concerned not only about their weight, but where they carry their weight in midlife.”
Dementia is an age-related condition that involves the loss of memory and other cognitive functions. It affects 5.7 million Americans, or about one in 10 people older than 65. Alzheimer’s disease is the most common form of dementia, accounting for 60 percent to 80 percent of cases.
“This ought to be a wake-up call to baby boomers in terms of diet and exercise,” said Dr. Sam Gandy, a spokesman for the Alzheimer’s Association who was not involved in the study. “If they are not frightened enough about heart disease, maybe they will worry about losing their mental function.”
Kaiser researchers studied 6,583 men and women in Northern California who had had their belly fat measured when they were 40 to 45. Some 36 years later, 16 percent had been diagnosed with dementia.
The Kaiser study found the risk for developing dementia was 2.3 times greater for men and women who were overweight and who had a large belly than for those with a normal weight and waist size.
The chance of developing dementia was 3.6 times greater for people who were obese and had large bellies than for people with normal weight and bellies.
By contrast, people who have parents or a sibling with Alzheimer’s disease face twice the risk of developing the disease.
Even people of normal weight who had bulging waist lines were at greater risk — almost two times higher — than those of normal weight without abdominal fat.
To determine belly fat, researchers used an instrument called a caliper to measure the distance from the back to the upper abdomen, midway between the top of the pelvis and the bottom of the ribs.
The Kaiser study was published in Wednesday’s online edition of Neurology, the medical journal of the American Academy of Neurology.
The research is the latest evidence that fat in the abdomen is the most dangerous kind. Previous studies linked the apple-shape physique to a greater risk of diabetes, heart disease and some cancers.
Researchers suspect that those fat cells are the worst because of their proximity to major organs. They ooze noxious chemicals, stoking inflammation, constricting blood vessels and triggering other processes that might also damage brain cells.
“There is a lot of work out there that suggests that the fat wrapped around your inner organs is much more metabolically active than other types of fat right under the skin,” Whitmer said. “It’s pumping out toxic substances. It’s very potent toxic fat.”
The study took into account high cholesterol, high blood pressure, heart disease and diabetes, Whitmer said. But a large belly remained a risk for dementia.
More research needs to be done to determine if reducing waist size can lower the risk factor for dementia, Whitmer said. Researchers don’t know if the study participants who had large bellies in their 40s lost the fat before developing dementia in their 70s, she said.
But other studies have found a positive effect on high cholesterol and glucose levels with a smaller belly, Whitmer said.
Some experts were skeptical, saying this kind of study cannot rule out the possibility that whatever is making people gain weight in their bellies in their 40s also puts them at risk for dementia in their 70s.
“There could be a connection. I’m not saying there couldn’t be,” said Barbara Corkery, director of Boston University’s obesity research center. “But it could be those two things are caused by the same root cause.”
Material from The Fresno Bee, The Washington Post and the Los Angeles Times is included in this report.