Small, But Promising, Advances in War Against Alzheimer's
From drugs to vaccines, progress is reported
FRIDAY, Nov. 21, 2003 (HealthDayNews) -- Alzheimer's is a horribly intractable disease.
But the fight against the mind-wasting ailment has been marked by a recent series of encouraging, albeit incremental, advances.That's a message worth sharing during November, National Alzheimer's Disease Awareness Month.
The latest of these small steps came in September when a U.S. Food and Drug Administration (FDA) advisory committee recommended approval of the drug memantine, which seems to slow the progression of moderate and severe Alzheimer's.
While the FDA is under no obligation to accept this recommendation, the agency often follows the advice of its committees. A decision is expected by the end of the year, and if memantine is approved, it would be the first drug for later-stage Alzheimer's.
There are few medications on the market geared specifically for Alzheimer's and they have only limited effectiveness. Memantine provides a ray of hope because it has a different mechanism of action: it blocks the overproduction of a brain chemical called glutamate.
The current mainstays of Alzheimer treatment, called cholinesterase inhibitors, work by boosting levels of another brain chemical, acetylcholine. Cholinesterase inhibitors are approved for use against mild and moderate forms of the disease.
"It's always exciting when you find something that works in a different way because it suggests that people for whom one drug doesn't work, another one may," says William Thies, vice president of medical and scientific affairs for the Alzheimer's Association in Chicago.
"It also opens up the possibility that the medications can be used together," Thies says.
Adds Dr. Marshall Keilson, co-director of the Memory Disorders Program at Maimonides Medical Center in New York City: "We're excited because it [memantine] represents a new approach. It's the beginning of a new category of treatments of Alzheimer's."
"It's not a miracle drug, and it's by no means a cure," adds Keilson, "but it's a fresh view of treating patients with Alzheimer's."
Some 4.5 million Americans have Alzheimer's disease, which primarily affects older people and is characterized by the progressive loss of memory and other cognitive skills. An estimated 11.3 million to 16 million seniors are likely to have the disease by 2050, the Alzheimer's Association predicts.
None of the available or soon-to-be-available medications for Alzheimer's attack the underlying cause of the disease, only the symptoms. That's because doctors don't know the exact cause or causes of the disease.
The approved cholinesterase inhibitors elevate the levels of acetylcholine. But, Keilson points out, "since the role of this chemical in producing Alzheimer's is uncertain and may be late in the course of the pathology, there's a certain limitation to what the medications can do." They have been shown to slow progression of the disease in a certain percentage of patients. And some people were able to resume watching television, reading a newspaper or carrying on a conversation, he says.
Research is currently being conducted to see if drugs that have been approved for other conditions might be able to prevent or treat Alzheimer's patients. They include nonsteroidal anti-inflammatory drugs or cholesterol-lowering statins, but the jury is still out on these medications.
On other fronts, certain drugs are being developed specifically for Alzheimer's.
"If there's one thing that is different today about Alzheimer's research than 20 years ago is that we've got this huge wealth of basic information about how the disease develops and what the fundamental biochemistry is," Thies says. "All of that information gives us an opportunity to intervene."
Scientists don't yet know where to intervene but they're hot on the trail. One of the main areas of research has been into strategies to limit the production of amyloid, a protein that collects in the brains of patients with Alzheimer's.
An experimental human vaccine apparently succeeded in eliminating some of these protein clusters, but may also have caused meningoencephalitis -- or swelling of the brain. The trial was halted last year but data is still being gathered and there is talk that the vaccine has been modified and may be tried again.
Other studies are looking at compounds that would affect different enzymes implicated in the protein buildup in the brains of Alzheimer's patients.
Because many of the risk factors for Alzheimer's are similar to those for heart disease, there has been speculation on the role of diet in preventing Alzheimer's. Although diet and nutrition is a notoriously difficult area to study, "it is perfectly reasonable to say that there's a lot of good reason to adopt a lifestyle that leads to healthy aging," Thies says.
That's about all that the scientific community knows right now and, until researchers uncover a cause or causes of Alzheimer's, there's unlikely to be a major breakthrough.
"As many treatment there are, there are that many potential causes and until we find out the real cause, we'll just keep fishing around," Keilson says.