Scientists are working on a nasal vaccine to try to reduce brain plaque seen in Alzheimer's disease.

So far, the vaccine has only been tested on mice, not people.

"It works in mice," researcher Howard Weiner, MD, tells WebMD. "I think the significance of the experiment is we've discovered a unique way of vaccination that may be of help for Alzheimer's.

"We think it's very exciting. The next step is to see whether it's safe in humans and then we can test to see how efficacious it is," says Weiner. He is the co-director of the Center for Neurologic Diseases at Boston's Brigham and Women's Hospital and Harvard Medical School, and the director of the Partners Multiple Sclerosis Center at Brigham and Women's Hospital.

Results of vaccine tests on mice appear in The Journal of Clinical Investigation.

Vaccine's Ingredients

The vaccine mixes an FDA-approved multiple sclerosis [MS] drug and an additional substance that helps the vaccine stimulate immunity. The nasal vaccination can be given as a spray or as drops. Drops were used on the mice in Weiner's study.

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Study's Results

The study focused on mice with an Alzheimer's-like brain disease. The mice got vaccine treatments and boosters for several weeks.

The vaccine is designed to activate brain cells called microglia. The microglia, in turn, are supposed to clean up a protein called beta-amyloid, which is found in brain plaques seen in Alzheimer's disease.

After the nasal vaccine treatments, total beta-amyloid levels dropped 73 perent, write the researchers.

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Surprise Discovery

Why did Weiner's team decide to make a nasal vaccine from those particular drugs?

They had been trying to figure out why another Alzheimer's vaccine hadn't worked. That vaccine had directly targeted beta-amyloid with antibodies, but side effects stopped trials of that vaccine in people.

"During that time, we made the unexpected discovery that if we gave the animals a type of disease that's like MS [multiple sclerosis], it cleared 80 perent of the beta [amyloid] from the brain. And when we made that discovery, the question was, how is this happening and can we take the discovery and find a way to use it to come up with a new vaccine for Alzheimer's," says Wiener.

The nasal vaccine doesn't stimulate the body to make antibodies. "In fact, in the animal models, it worked in mice that are genetically unable to make antibodies, so it's a totally unique type of vaccine from all the other vaccines that have been tried," says Weiner.

Beta-amyloid deposits are a bit different in mice and people, and the vaccine's long-term results aren't known yet, write the researchers.

Another researcher who worked on the study is an employee of and has shares in ID Biomedical Corporation of Quebec, the nasal treatment's maker, the journal notes.

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By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Frenkel, D. The Journal of Clinical Investigation, Aug. 11, 2005; online edition. Howard Weiner, MD, co-director, Center for Neurologic Diseases, Brigham and Women's Hospital/Harvard Medical School; director, Partners Multiple Sclerosis Center, Brigham and Women's Hospital. News release, The Journal of Clinical Investigation.