Brain starvation as we age appears to trigger Alzheimer's; exercise, diet possible preventive strategy

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Public release date: 24-Dec-2008

http://www.eurekalert.org/pub_releases/2008-12/nu-bsa122308.php

Contact: Marla

Marla-@...

Northwestern University

Brain starvation as we age appears to trigger Alzheimer's

Improving blood flow to brain is a preventive strategy

CHICAGO --- A slow, chronic starvation of the brain as we age appears to

be one of the major triggers of a biochemical process that causes some

forms of Alzheimer's disease.

A new study from Northwestern University's Feinberg School of Medicine

has found when the brain doesn't get enough sugar glucose -- as might

occur when cardiovascular disease restricts blood flow in arteries to

the brain -- a process is launched that ultimately produces the sticky

clumps of protein that appear to be a cause of Alzheimer's.

Vassar, lead author, discovered a key brain protein is altered

when the brain has a deficient supply of energy. The altered protein,

called elF2alpha, increases the production of an enzyme that, in turn,

flips a switch to produce the sticky protein clumps. Vassar worked with

human and mice brains in his research.

The study is published in the December 26 issue of the journal Neuron.

" This finding is significant because it suggests that improving blood

flow to the brain might be an effective therapeutic approach to prevent

or treat Alzheimer's, " said Vassar, a professor of cell and molecular

biology at the Feinberg School.

A simple preventive strategy people can follow to improve blood flow to

the brain is getting exercise, reducing cholesterol and managing

hypertension.

" If people start early enough, maybe they can dodge the bullet, " Vassar

said. For people who already have symptoms, vasodilators, which increase

blood flow, may help the delivery of oxygen and glucose to the brain, he

added.

Vassar said it also is possible that drugs could be designed to block

the elF2alpha protein that begins the formation of the protein clumps,

known as amyloid plaques.

An estimated 10 million baby boomers will develop Alzheimer's in their

lifetime, according to the Alzheimer's Association. The disease usually

begins after age 60, and risk rises with age. The direct and indirect

cost of Alzheimer's and other dementias is about $148 billion a year.

The initial trigger of Alzheimer's has long been a mystery.

Ten years ago, it was Vassar who discovered the enzyme, BACE1, that was

responsible for making the sticky, fiber-like clumps of protein that

form outside neurons and disrupt their ability to send messages.

But the cause of the high levels of the protein in people with the

disease has been unknown. Vassar's study now shows that energy

deprivation in the brain might be the trigger starting the process that

forms plaques in Alzheimer's.

Vassar said his work suggests that Alzheimer's disease may result from a

less severe type of energy deprivation than occurs in a stroke. Rather

than dying, the brain cells react by increasing BACE1, which may be a

protective response in the short term, but harmful in the long term.

" A stroke is a blockage that prevents blood flow and produces cell death

in an acute, dramatic event, " Vassar said. " What we are talking about

here is a slow, insidious process over many years where people have a

low level of cardiovascular disease or atherosclerosis in the brain.

It's so mild, they don't even notice it, but it has an effect over time

because it's producing a chronic reduction in the blood flow. "

Vassar said when people reach a certain age, some may get increased

levels of the enzymes that cause a build-up of the plaques. " Then they

start falling off the cliff, " he said.

--

ne Holden, MS, RD

" Ask the Parkinson Dietitian " http://www.parkinson.org/

" Eat well, stay well with Parkinson's disease "

" Parkinson's disease: Guidelines for Medical Nutrition Therapy "

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