FWIW - Reuters report on possible reversibility of memory loss in Alzheimers

[Guest guest]

This is a surprise finding from one of those animal models that may

or may not provide meaningful information about the human disease

it's used to explore.

I thought it was worth posting because of the hopeful implications

about reversibility of symptoms and because the therapeutic agent

that reversed memory loss in the lab mice was, interestingly enough,

doxycycline.

http://tinyurl.com/b42nk

Mouse study suggests Alzheimer's damage reversible

By Maggie Fox, Health and Science Correspondent

1 hour, 41 minutes ago

WASHINGTON (Reuters) - Tests on mice suggest the brain damage caused

by Alzheimer's disease may be at least partly reversible,

researchers reported Thursday.

Their genetically altered mice regained the ability to navigate

mazes after the genes that caused their dementia were de-activated.

This suggests that the brain damage caused by Alzheimer's is not

permanent, they wrote in their report, published in the journal

Science.

" I was astonished. I didn't believe the results when I saw them, "

said Alzheimer's researcher Ashe of the University of

Minnesota, who led the study.

" When I saw the memory getting better I actually thought I had done

something wrong in the experiment. "

Alzheimer's is a brain-destroying disease that affects an estimated

4.5 million people in the United States alone and millions more

globally. As the population gets steadily older, experts estimate

this number will balloon to as many as 16 million by 2015 in the

United States.

Outward symptoms start with memory loss, which progresses to

complete helplessness as brain cells are destroyed. In the brain,

neurons die as messy plaques and tangles of protein form.

The two proteins involved are unhealthy forms of natural brain

compounds called amyloid beta and tau protein.

Ashe's team worked with mice genetically engineered to develop the

mutant tau, but this mutation could be stopped -- or de-activated --

with use of a drug called doxycycline.

As expected, the mice developed dementia and had brain atrophy

similar to human Alzheimer's disease.

And when the engineered gene was turned off, memory loss stopped, as

expected. But the mice did not merely stop getting worse. They got

better.

" Even mice that had lost half the neurons that are involved in

forming memories, when we removed the molecule causing the memory

loss from the remaining neurons by turning off the genes, the mice

were able to learn and remember new information, " Ashe said in a

telephone interview.

" No one suspected so many neurons would still be able to function. "

FROM MICE TO MEN

She noted that it is a long way from treating a mouse to treating a

person.

" How are we ever going to turn off the gene in humans? " Ashe asked.

What might be possible, she said, would be stopping the production

of the mutant proteins. And current vaccine efforts are aimed at

removing the bad proteins from the brain.

" The point that makes us hopeful is the remaining neurons were

functioning, " she said. " When we removed the molecules that

presumably were causing the malfunction, the mice were able to

perform better. "

Ashe said her team used a swimming maze test, in which mice must

swim and find an underwater platform to stand on.

" The maze situation is very similar to parking a car in the parking

lot and remembering where you parked it, " she said.

Thies, vice president for medical affairs at the Alzheimer's

Association, said at the very least the mouse would be a useful tool

for testing new therapies.

" It at least opens the possibility that people will get better, "

Thies said in a telephone interview.

The other interesting finding, Ashe said, was that the tangles of

brain cells were not in themselves, evidently, toxic to surrounding

brain tissue.

" The neurofibrillary tangles, which are one of two major

pathological hallmarks of Alzheimers disease, turn out not to be

involved in causing memory problems, at least in mice, " she said.

Some process may be going on at a microscopic level, and the tangles

may be a result but not a cause of the brain damage, she said.