Australian researchers believe they have discovered why foods high in
saturated fat increase the likelihood of developing Alzheimer's disease.

Researchers from Curtin University of Technology in Perth, found that
saturated dietary fat damages the lining of blood vessels in the brains
of mice, allowing a protein called amyloid to enter the brain.

The study, to be published in the British Journal of Nutrition, is one
of the first to demonstrate a scientific link between diet and
Alzheimer's disease.

"In the past population studies suggested that high fat diets may be a
risk factor for Alzheimer's disease, but no one really understood why,"
says Professor Mamo, co-author of the study and National Director of the
Australian Technology Network's Centre for Metabolic Fitness.

"The brain has millions of blood vessels. Each vessel has a lining that
is very selective about what is allowed to go in and out, and this keeps
the brain in good health."

Mamo and colleagues found this lining, called the blood-brain-barrier,
is damaged by high saturated fat diets.

"This allows things to be getting in there that shouldn't be," says Mamo.
Amyloid build-up

A key feature of Alzheimer's disease is amyloid deposits in the brain,
which cause inflammation and nerve cell death.

Amyloid is produced in the small intestine, and secreted into the blood
where it attacks the blood-brain-barrier.

"When the blood vessel lining gets disrupted and deregulated you get
delivery of amyloid into the brain," says Mamo.

Past research has shown that saturated dietary fats increase the
production of amyloid in the small intestine.
Mouse models

In the study, the researchers fed mice a diet of either saturated,
monounsaturated or polyunsaturated fats, and compared them to mice
genetically designed to develop Alzheimer's.

Within two months, the mice that were fed a saturated fat diet showed
significant change in their blood vessels.

"We saw a very substantial deterioration in the mice blood vessel
architecture," says Mamo. "But, we saw no deterioration in the mice fed
monounsaturated or polyunsaturated diets."

The saturated fat mice also had more amyloid deposits in their brain
than those fed the monounsaturated or polyunsaturated diets.

The researchers also found that the brains of the mice fed the saturated
fat diet were remarkably similar to the Alzheimer's mouse models.

"In mice that have been genetically manipulated to overproduce amyloid,
we find exactly the same kind of pathology," says Mamo.

Using antibodies with a fluorescent tag the researchers were able to
confirm that dietary fats are also found inside the amyloid deposits.

The researchers believe their study will provide a new target for
Alzheimer's drug treatments, which are directed at improving nerve cells.

"We need to refocus our strategy to protect these vessel walls and to
restore health to damaged vessels," says Mamo.
Gene markers

The announcement comes at the same time as a French-led study announced
the discovery of two genes associated with Alzheimer's.

The study, published in the journal Nature Genetics, is the largest ever
genome study focused on Alzheimer's.

One of the genes, CLU, produces a protein called clusterin, which is
known to reduce the inflammation caused by amyloid deposits.

The other gene, known as PICLAM, is important for maintaining
communication between nerve cells in the brain.

Study co-author Dr Corinne Lendon of the Queensland Institute of Medical
Research says the study should improve their understanding of
Alzheimer's and will hopefully lead to better detection of the disease.

On Wed, 16 Sep 2009 06:38:53 +0800, Phil..c wrote:

> "The brain has millions of blood vessels. Each vessel has a lining that
> is very selective about what is allowed to go in and out, and this keeps
> the brain in good health."
>
> Mamo and colleagues found this lining, called the blood-brain-barrier,
> is damaged by high saturated fat diets.

Cool! This means that we'll need less recreational drugs to get the
same high!

-sw