Researchers describe new era in experimental chemical attacks on Alzheimer’s disease

July 11, 2000
Web posted at: 3:55 p.m. EDT (1955 GMT)

In this story: Encouraging vaccine results Much remains to be done RELATED STORIES, SITES

From staff reports

WASHINGTON (CNN) -- Neutralizing harmful brain enzymes and stopping tissue inflammation are among the leading scientific attacks on Alzheimer’s disease, researchers reported Tuesday.

"We're into the era of Alzheimer’s therapeutics," said Dr. Dennis Selkoe of Harvard University. He and other scientists were attending the World Alzheimer Congress 2000, a gathering of researchers from many countries.

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The tragedy of Alzheimer's

The debilitating brain disease, which primarily strikes the elderly, now afflicts more than 12 million patients -- and affects millions more people who are members of their families and often act as care-givers.

The researchers also received a report from Elan Pharmaceuticals that an experimental vaccine designed to fight Alzheimer's disease appears to be safe in humans.

"It's gone remarkably smoothly. In the U.S. we've done single-dose studies, and they're nearly complete, and so far things have gone remarkably well. We've not encountered any problems at all in Alzheimer's patients themselves," Dr. Dale Schenk, vice president of discovery research at Elan Pharmaceuticals told CNN Medical News.

"By the end of the year," he added, "we hope to make significant conclusions from those phase one studies, so that sometime in 2001 we can actually begin the key pivotal studies to see just how the vaccine's working."

Referring to the multiple approaches to stop or prevent Alzheimer's, Selkoe of Harvard and Brigham and Women’s Hospital, Boston, said, "You have to have an understanding of the causes and mechanisms to really devise potent treatment. I think that’s where we are now."

Using nonsteroid drugs to counter brain-tissue inflammation offers another avenue of promise. Dr. Joseph Rogers of Sun Health Research Institute said, "Over the last decade it’s been shown that virtually all the inflammatory molecules that could be observed in the twisted fingers of an arthritis patient can be observed in the brains of Alzheimer’s disease patients."

Experiments are under way to test the theories on inflammation and the other vectors of attack. If the studies go well, Alzheimer’s patients could see therapies available in 3 to 5 years.

The current safety trials by Elan Pharmaceuticals on the potential vaccine are taking place in the United States and United Kingdom. When they're completed, the studies will expand to include several hundred patients at a number of medical institutions.

"Assuming everything works out, this vaccine not only will treat Alzheimer's disease, but will also prevent Alzheimer's. It will completely change the face of Alzheimer's therapeutics now and forever if it works," said Dr. Ivan Lieberburg, executive vice president and chief science and medical officer for the Elan Corporation.

One year ago Elan researchers reported remarkable results of the vaccine in mice. Mice immunized at a young age were protected from Alzheimer's. In animals that already had the disease, the disease was halted and in some cases reversed.

"The amount of reduction of brain pathology was truly remarkable. It was as much as 99 percent reduced in animals that were treated with this vaccine," said Schenk.

Two other research teams have verified Elan's promising results in mice. They've taken the work a step further, showing the vaccine produced improvements in behavior.

In addition, researchers and Brigham and Women's Hospital report encouraging results with a similar, nasal vaccine. "There is a 50-60 percent decrease in the amount of amyloid plaques and indeed the amount of a-beta proteins in the brains of mice who have gotten chronic nasal treatment," their report said.

Although it will take time to see if humans have the same results, other researchers say the safety trial results are encouraging.

"I think the vaccine immunization hypothesis is very exciting," said Dr. Ronald Peterson of the Mayo Clinic. "There is a lot of work that needs to be done with regards to its safety, its effectiveness, whether it will work in humans as it has in mice. But nevertheless, the major hypothesis is still very interesting for the possibility of prevention of the disease."

The vaccines are designed to attack the characteristic brain plaques of Alzheimer's. There is still some debate over whether the amyloid plaques are the cause of Alzheimer's dementia. The final outcome of the vaccine studies in humans should either prove or disprove the amyloid plaque theory as the cause of the disease.

Alzheimer’s causes progressive memory loss and dementia as well as weight loss, incontinence and difficulty in physical tasks like walking with steadiness. Many patients enter a vegetative state. From the onset of symptoms until death, the average is 8 years but may range from 3 to 20 years, according to the Alzheimer’s Association.

Although there is no cure for Alzheimer's, there are currently three drugs approved to treat symptoms of the disease.

CNN Medical Correspondent Rhonda Rowland contributed to this report.

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