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Alzheimer's Drug May Slow Down Disease

Exelon Seemed to Help Some Patients for 5 Years

By Salynn Boyles
WebMD Health News

Feb. 25, 2004 -- There remains some debate about whether a relatively new class of drugs used to treat the symptoms of Alzheimer's can slow disease progression. While newly reported findings show they can for some patients, an Alzheimer's expert who spoke to WebMD says the evidence remains inconclusive.

In a presentation delivered this week at the American Association for Geriatric Psychiatry annual meeting in Baltimore, Alzheimer's disease researcher Gary W. Small, MD, reported that the Novartis Pharmaceuticals drug Exelon appeared to slow disease progression in 83 patients with mild to moderate Alzheimer's disease who took it for five years.

The patients were the only ones among roughly 2,000 original participants in four separate Exelon studies still taking the drug five years later. The 83 patients continued to experience mental declines while on Exelon, but most did not progress to the severe cognitive decline that would have been expected without treatment.

Although there is no cure for Alzheimer's disease, and with time the disease get progressively worse, some patients with mild to moderate Alzheimer's disease were more likely to show improvement while taking the drug than those taking placebo.

"This tells us that there is a subset of patients who appear to do better than they would have if they stay on this medication," Small tells WebMD. "It suggests these drugs can work for long periods. It also lets clinicians know that if a patient has tolerated this medication well and continues to have a reasonable quality of life they should probably stay on it."

AD Drugs Don't Work for all Patients

Exelon is among a group of drugs known as cholinesterase inhibitors, which boost levels of a key neurotransmitter linked to brain function. This chemical called acetylcholine helps with memory and learning. In Alzheimer's disease nerves degeneration results in decreasing levels of this neurotransmitter substance. This decrease is linked closely with cognitive deficits in patients.

Other cholinesterase inhibitors approved to treat mild to moderate Alzheimer's disease include Pfizer's Aricept; Warner Lambert's Cognex; and Janssen Pharmaceutical's Reminyl.

Alzheimer's Association spokesman Bill Thies, PhD, tells WebMD that roughly one-third of Alzheimer's patients who go on the drugs have "robust" responses, while the remaining patients either have "mediocre" responses or don't respond at all.

"These drugs don't take people with severe Alzheimer's disease and return them to normal. The impact is much more modest," he says. "As a class they have done a lot of good, but they don't work for everyone."

Thies says the claim that the drugs slow Alzheimer's progression is "still highly debatable," adding that most clinical trials comparing treated patients to nontreated patients have shown little difference in the rate of mental decline.

"The people who stayed on (Exelon) in this study were the ones who had the best results, and it is certainly possible that they had the slowest progressing disease to begin with," he says.

Some Patients Continue to Benefit

As a group the 83 patients did have slightly milder mental impairment at study entry than the general study population.

Although all the participants in the study did have a progressive decline in mental functions during the five-year study period, those treated with Exelon progressed slower compared with untreated patients.

"For patients who are helped by this drug, it may work for longer periods than we have realized," Small tells WebMD. "I think that is the key message."

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