A team led by researchers at the Farber Institute for
Neurosciences at Thomas Jefferson University in Philadelphia and Edith
Cowan University in Joondalup, Western Australia has shown that being
extremely overweight or obese increases the likelihood of developing
Alzheimer’s. They found a strong correlation between body mass index and
high levels of beta-amyloid, the sticky protein substance that builds up
in the Alzheimer’s brain and is thought to play a major role in
destroying nerve cells and in cognitive and behavioral problems
associated with the disease.
“We looked at the levels of beta-amyloid and found a
relationship between obesity and circulating amyloid,” says Sam E.
Gandy, M.D., Ph.D., director of the Farber Institute for Neurosciences.
“That’s almost certainly why the risk for Alzheimer’s is increased,”
says Dr. Gandy, who is also professor of neurology, and biochemistry and
molecular biology at Jefferson Medical College of Thomas Jefferson
University. “Heightened levels of amyloid in the blood vessels and the
brain indicate the start of the Alzheimer’s process.” The scientists
reported their findings this month in the Journal of Alzheimer’s
Disease.
According to, Dr. Gandy, evidence has emerged over
the last five years that many of the conditions that raise the risk for
heart disease such as obesity, uncontrolled diabetes, hypertension and
hypercholesterolemia also increase the risk for Alzheimer’s. Yet exactly
how such factors made an individual more likely to develop Alzheimer’s
remained a mystery.
Dr. Gandy, Ralph Martins, Ph.D., of Edith Cowan
University and their colleagues measured body mass index and beta-amyloid
levels in the blood. They also looked at several other factors
associated with heart disease and diabetes, such as the inflammatory
marker C-reactive protein, insulin, and high density lipoprotein in 18
healthy adults who were either extremely overweight or obese. They found
a “statistically significant correlation” between body mass index and
beta-amyloid.
“Ours is one of the first attempts to try to find out
on both the pathological and the molecular levels how obesity was
increasing the risk of Alzheimer’s,” says Dr. Gandy, who serves as
chairman of the Alzheimer's Association’s Medical and Scientific
Advisory Council.
One implication of these findings could be that by
losing excess weight and maintaining normal body weight, an individual
might reduce the risk of developing Alzheimer’s. However, this has not
been proven, notes Dr. Gandy.
“What’s especially interesting about this is that
several studies are showing that even medical conditions in midlife may
predispose to Alzheimer’s later on,” he says. “The baby boomers today
should pay attention to this. Their medical risk factors today will play
a role 30 years later. Think about weight, cholesterol, blood pressure,
which could affect you long-term. In terms of Alzheimer’s, another risk
factor is maintaining an active mental lifestyle.”
The next step is to follow such patients over the
long term to see how many do indeed develop Alzheimer’s. “We need to
first develop a medicine that is effective in humans in lowering amyloid
accumulation or generation,” says Dr. Gandy. “We have those now in mice
and we are testing them in humans. If we can develop such a medicine,
then the question will be, if we can lower amyloid, will that in fact
prevent Alzheimer’s?”
Source:
Thomas Jefferson University Hospital
Published on 6th
January 2006
