Does Alzheimer's Disease Have a Zinc Link?

Mouse study finds trace metal plays a role

MONDAY, April 29, 2002 (HealthDayNews) -- In the ongoing quest to find the cause of Alzheimer's disease, Korean scientists have discovered a possible new player: zinc.

Studies in genetically manipulated mice found zinc released by nerve cells played an important role in the development of an Alzheimer-like condition in those animals, says a report in tomorrow's issue of the Proceedings of the National Academy of Sciences.

Mice bred to lack a gene required for the normal transport and release of zinc by nerve cells developed a large number of the amyloid plaques that are one of the hallmarks of Alzheimer's disease, say researchers from the University of Ulsan College of Medicine in Seoul.

The two notable changes that accompany the onset of this disease are formation of plaques, abnormal protein deposits outside nerve cells in the brain, and tangles, abnormally twisted fibers inside those nerve cells. Efforts to prevent or treat Alzheimer's disease are focused on preventing formation of plaques. This is generally done by attacking the beta-amyloid peptide, the major protein found in the plaques.

The finding suggests the use of compounds that bind to zinc and remove it from the body "may be an alternative therapeutic strategy to slow or prevent the onset of Alzheimer's disease," the researchers write.

It's an interesting idea that comes from "really heavyweight biochemistry of Alzheimer's disease," but one that requires a lot more work before it can be put to use, says Bill Thies, vice president for medical and scientific affairs of the Alzheimer's Association.

"People have noticed an association of zinc in plaques for some time," Thies says. "Zinc is an interesting metal. There are lots of places in the body where it is used to facilitate protein binding -- for example, it is a component of particles that contain insulin."

However, the Korean report is "a real basic science paper, probably with no immediate clinical significance," Thies says. "Whether this has any long-term meaning about treating the disease is hard to tell."

He says he doesn't want to see a scare comparable to the one that occurred several years ago when reports found a possible link between aluminum and Alzheimer's disease. "The legend was that aluminum was related to the disease, and it had some people throwing out their aluminum pots and pans," Thies says of the now-discredited reports.

"And there has been some stuff recently about iron, and how iron metabolism might be involved in Alzheimer's," he says. Like the zinc report, the iron work requires a lot more study, he adds.

Dr. Jae-Young Koh, lead author of the paper, says he has no immediate plans for human studies. However, he sees a possible medical application of chelators, chemicals that bind to metal atoms. He cites a study finding that one chelator, clioquinol, "was quite effective in reducing the plaque load in a transgenic mouse model for Alzheimer's disease."

Nutritionally, zinc is a trace element that is essential for such processes as development of the reproductive organs and wound healing. It is known to be involved in the control of more than 100 proteins and nucleic acids. It is found in lean meat, whole-wheat breads, beans and seafood. It is also a component of many multivitamin products.

What To Do: You can catch up with the latest on Alzheimer's disease research and treatment efforts from the Alzheimer's Association or the National Institute for Neurological Disorders and Stroke.

SOURCES: Bill Thies, Ph.D, vice president, medical and scientific affairs, Alzheimer's Association, Chicago; Jae-Young Koh, M.D., Ph.D, director, Center for the Study of CNS Zinc, University of Ulsan College of Medicine, Seoul; April 30, 2002, Proceedings of the National Academy of Sciences
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