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Drug That Slows Progression to Alzheimer's May Change Treatment Timing: Study

Posted on: Wednesday, 13 April 2005, 21:00 CDT

TORONTO (CP) - A drug has been shown for the first time to slow the slide into Alzheimer's disease in patients with mild cognitive impairment, although it doesn't stop the devastating condition from occurring, U.S. and Canadian researchers say.

Furthermore, the researchers found that vitamin E had no effect in holding back the progression into Alzheimer's, a disease that affects more than 400,000 Canadians over age 65.

The study, published online Wednesday in the New England Journal of Medicine, showed that the drug donepezil kept the symptoms of Alzheimer's at bay for about the first 12 months of treatment.

However, the drug's effects were short-lived. By the end of the three-year trial, patients treated with donepezil had the same risk of developing Alzheimer's as those given vitamin E or a placebo.

Despite the therapy's shortcomings, the investigator who led the three-year study was upbeat about the results.

"Our findings represent an important shift in the field of Alzheimer's disease treatment, in that this is the only study to date to demonstrate the ability to push back the clinical diagnosis of the disease," said Dr. Ronald Petersen, a neurologist at the Mayo Clinic in Rochester, Minn.

For one subgroup of patients, the effects of donepezil lasted longer - up to two years or more. These patients have a genetic profile called Apolipoprotein E4, which is also known to increase the likelihood of developing Alzheimer's.

But by study's end, those with the genetic profile had the same risk for getting Alzheimer's disease as other participants.

"One has a little bit of ambivalence about it because the hope was to prevent decline for a longer period of time," said Dr. Sandra Black, head of neurology at Sunnybrook and Women's Health Sciences Centre in Toronto.

"That hope was not achieved," said Black, who was among researchers from 69 centres across the United States and Canada involved in the study of 769 patients with mild cognitive impairment, or MCI. Patients were randomized to three groups, in which they were treated with either donepezil, vitamin E or a dummy pill.

The hallmark of MCI is impaired memory; the condition is considered a transitional stage between the forgetfulness of normal aging and the more serious memory decline and other cognitive problems associated with Alzheimer's disease.

MCI goes beyond common age-related memory lapses, said Black. "This is where there's a significant problem remembering things that happened a few minutes ago or 10 minutes ago or an hour ago, but where it begins to be quite noticeable."

While donepezil, sold in Canada under the brand name Aricept, did not achieve the hoped-for results, she said the study may mean treatment should be started earlier, once symptoms of MCI become evident.

"Alzheimer's doesn't start all of a sudden out of the blue. In fact, people think it's incubating in the brain for three or four decades," Black said. "I think what it means is that we have to keep working hard to find a treatment that really affects the disease course, not just the symptoms of the disease."

Petersen agrees, saying the results may shift researchers towards earlier intervention, "laying the groundwork for testing other drugs."

Dr. Jack Diamond, scientific director of the Alzheimer Society of Canada, said he would like to see more studies with far more participants - in the thousands, rather than the hundreds - to see if there are other subgroups of MCI patients who might benefit from donepezil or other drugs in its class.

Those drugs are known as cholerinase inhibitors, and they are already used to slow the progression of symptoms in people who have full-blown Alzheimer's.

Still, they are not a cure - they can't stop Alzheimer's from developing nor reverse the damage once it's been done, Diamond said.

"But a cure will come along one day. So it's very important to identify MCI, because that's the time to apply a genuine treatment."

Source: Canadian Press

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