MONDAY, Nov. 10, 2003 (HealthDayNews) -- Copper has cropped up as a possible culprit in Alzheimer's disease, but two new studies turn that penny on its head.
Researchers say mice with more copper in their brain cells are less likely to develop the toxic protein fragments called amyloid-beta associated with Alzheimer's. In one study, German scientists found mice with a genetic predisposition to the brain disease lived longer and had less amyloid-beta when they drank copper-laced water than did those that didn't get the supplements.
In a second study, scientist in Canada and the United States showed that mutant mice with high amounts of copper in their brain cells had about half the amyloid-beta buildup as mice without the mutation. The size of the effect was as great as that of experimental vaccines that target the harmful proteins, says study leader David Westaway, a brain researcher at the University of Toronto.
"There has been the suggestion that elevations of copper can help drive Alzheimer's disease, but we don't get that," Westaway says. "When we drove up levels of copper in the brain, some of the hallmarks of Alzheimer's disease improved."
Thomas Bayer, a neuroscientist at Saarland University Medical Center, in Homburg/Saar, Germany, and leader of the other study, says, "If you give mice copper, either in water or by genetic manipulation, you reduce amyloid-beta" and prolong their life.
Both papers appear in this week's issue of the Proceedings of the National Academy of Sciences.
How copper and amyloid-beta are related isn't clear. However, Bayer's group believes the link involves an enzyme in the brain called beta-amyloid precursor protein, or APP.
Copper normally hooks up with this molecule. But as people age, their copper levels fall -- and APP is left without its metal mate. As a result, Bayer speculates, APP can generate the amyloid-beta proteins that destroy neurons.
"If copper is bound to APP, you don't get a-beta. If APP is copper-free, a-beta is produced directly," he says.
Bayer says the copper connection might help explain at least some of the "sporadic" cases of Alzehimer's disease, which account for as much as 95 percent of the total. The rest are due to gene mutations.
An estimated 4.5 million Americans have Alzheimer's disease, according to the Alzheimer's Association. The degenerative disorder has no cure, and drugs on the market to treat it serve only to delay the progression of dementia.
More information
Try the Alzheimer's Association or the National Institutes of Health.
