Study Links Middle-Age Belly Fat to Dementia

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By Rob Stein

Washington Post Staff Writer

Thursday, March 27, 2008; Page A02

People who have big bellies in their 40s are much more likely to get

Alzheimer's and other forms of dementia in their 70s, according to new

research that links the middle-aged spread to a fading mind for the first

time.

The study of more than 6,000 people found that the more fat they had in

their guts in their early to mid-40s, the greater their chances of becoming

forgetful and confused and showing other signs of senility as they aged.

Those who had the most expansive midsections faced more than twice the risk

of the leanest.

Surprisingly, a sizable stomach seems to increase the risk even among those

who are not obese or even overweight, the researchers reported in a paper

published online yesterday by the journal Neurology.

" A large belly, independent of total weight, is a potent predictor of

dementia, " said A. Whitmer, a research scientist at the Kaiser

Permanente Division of Research in Oakland, Calif., who led the new study.

The findings are alarming in light of America's growing girth, Whitmer and

other experts said.

" If these findings are replicated and better understood, it looks like an

unhealthy brain could be another consequence of this epidemic of obesity, "

said Lenore Launer of the National Institute on Aging.

The research is the latest evidence that fat in the abdomen is the most

dangerous kind. Previous studies have linked an apple-shaped physique to a

greater propensity for diabetes, heart disease and stroke. Researchers

suspect that belly 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 may 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. "

Whitmer and her colleagues analyzed data from 6,583 members of Kaiser

Permanente of Northern California who had had their belly fat carefully

calculated as part of a broad health study between 1964 and 1973. The

researchers examined whether there was link between abdominal obesity

between the ages of 40 and 45 and the chances of developing Alzheimer's and

other forms of dementia by the time the patients hit their 70s, between 1994

and 2006.

The risk for dementia, the researchers found, increased steadily with the

amount of fat in the abdomen, even after accounting for alternative

explanations, such as other diseases, bad habits and lower education. They

found no such association for fat in the thigh.

The researchers used a complicated method for measuring fat known as

sagittal abdominal diameter (SAD). Those with a SAD score above 25 --

roughly equivalent to a waist of at least 39 inches -- had the biggest

bellies and the greatest risk.

Previous studies have shown that people who are overweight are at increased

risk for dementia. But when the researchers examined patients' body mass

index (BMI), which is the most common way to determine whether someone is

overweight or obese, they found that people with big bellies were still

nearly twice as likely to develop dementia, even if they had BMIs that were

considered healthy. In fact, their risk was about the same as for those who

were overweight or obese.

" What that tells you is the effect of the belly is over and above of being

overweight, " Whitmer said. " One of the take-home messages is it's not just

your weight, but where you carry your weight in middle age, that is a strong

predictor of dementia. "

Stomach fat may increase the risk for dementia in the same ways it promotes

heart disease -- by boosting blood pressure and constricting blood flow,

said A. Luchsinger of Columbia University. He and others said it may

also promote the accumulation of amyloid, a substance found in the brains of

Alzheimer's patients.

" We think the buildup and clumping of this material is an important risk

factor, " said Sam Gandy of the Mount Sinai School of Medicine, who chairs

the Alzheimer's Association's medical and scientific advisory council.

Previous research has found that people who are obese have higher levels of

amyloid in their blood, he said.

Some experts remained 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. "

While acknowledging that more research is needed, Whitmer said the findings

provide one more reason to try to maintain a healthy weight, noting that

this type of fat is the most easily shed by dieting and exercise.

" It's not as stubborn as the fat under the skin, " she said. " It's a

modifiable risk factor. "