Alzheimer's Vaccine Dream Inches Closer to Reality

From the WebMD Archives

Dec. 20, 2000 -- The search for an Alzheimer's vaccine may get easier with the help of some Canadian researchers. A new study in the Dec. 21 issue of the journal Nature provides important evidence from animal research that a proposed Alzheimer's vaccine actually may work.

The vaccine triggers the immune system to ward off the production of excess amounts of a small protein called amyloid beta peptide in the brain -- a process widely thought to be responsible for causing Alzheimer's disease.

"The amyloid beta peptide appears to be the chief villain in the development in the disease," says senior researcher David Westaway, PhD. Both mice and humans make small amounts of the protein naturally, but when there is too much of it, brain cells die, resulting in Alzheimer's disease. Westaway is associate professor of laboratory medicine and pathobiology at the University of Toronto's School of Medicine.

Alzheimer's disease, the most common form of dementia, is a progressive, degenerative disease of the brain. According to the Alzheimer's Association, 4 million Americans have the disease, and unless a cure or a means of prevention is found, it's estimated that 14 million will have the disease by the middle of the century.

In a widely publicized study released this past summer, researchers showed that the vaccine -- developed by the Elan Corporation of Dublin, Ireland -- was successful in clearing amyloid beta peptide plaques from the brains of mice genetically engineered to have Alzheimer's disease.

In this latest research, a team of scientists was able to establish that vaccinated mice showed significant mental improvement only six weeks after being given the vaccine.

Westaway notes that the experiments were done with mice that mimicked the relatively mild first stages of Alzheimer's disease and that experiments with mice with more advanced Alzheimer's were "on the list" of future studies.

The vaccine works by introducing a form of the amyloid beta peptide that Westaway says is "99.9% pure" into the bloodstream. The immune system recognizes the invader and produces millions upon millions of immune cells to fight it.


"I think the work is very exciting," says learning and memory specialist, Paul Chapman PhD, professor of neuroscience at Cardiff University in Wales.

The vaccine already is being tested in humans. "I'm going to be a lot happier about those clinical trials in humans now that I know this procedure helps prevent [mental] decline in mice," Chapman says.

Vaccine developer, Dale Schenk, PhD, tells WebMD that the first phase of human testing is almost complete and that all indications are that it's safe. Further testing for proper dosage and effectiveness is slated to begin toward the end of 2001. If things go well, the vaccine could be generally available in four to seven years, according to Schenk.

"We're starting it out as a treatment for mild to moderate Alzheimer's disease," says Schenk, "but one might also consider prevention with this too."

"Although this is a work in progress, this is very exciting news," says Steve Rudin, executive director of the Alzheimer's Society of Canada. "Could this change the demographics of Alzheimer's disease? You bet it could," he says.