April 2, 2003
The first drug found to be effective against the moderate to severe stages of Alzheimer's disease offers new promise for treating the illness at a time when patients and caregivers need it most.
The drug, called memantine, works in a novel way to prevent damage to brain cells, slowing the mental and physical deterioration seen in the later stages of the disease, according to the results of a large, well-designed study conducted at multiple major medical centers.
"This is a major breakthrough," says the study's lead author Barry Reisberg, M.D., professor of psychiatry and director of the Zachary and Elizabeth M. Fisher Alzheimer's Disease Education and Resources Program at New York University Medical Center. "Patients deteriorated about half as much as they otherwise would have over the six months of the study." The drug also appeared to be remarkably safe and free of side effects.
The later stages of Alzheimer's disease are a particularly stressful time for families and patients, who become increasingly unable to wash, bathe, and care for themselves. Currently available Alzheimer's drugs, such as Aricept, Exelon, and Reminyl, offer little benefit during this time. This new pill offers hope for millions with the disease to remain independent longer, easing the burden on caregivers.
"The main benefit of memantine comes late in the illness and appears to have some impact on the quality of life of the patient as well as the caregiver," observes Samuel Gandy, M.D., Ph.D., Chairman of the Scientific Advisory Board of the Fisher Center for Alzheimer's Research Foundation. However, he cautions that caregivers not raise their expectations too high. "The improvements can be very subtle. Researchers might see definite drug effects when families might not notice any change."
In addition, Dr. Gandy points out that scientists disagree on whether the drug has any benefits against the underlying causes of Alzheimer's itself, including the death of brain cells. "New experimental medicines that target these fundamental changes in the disease are now in clinical trials and hold promise for arresting, preventing, or perhaps even reversing brain degeneration," he says.
Not Yet for Sale
Memantine is not yet available at U.S. pharmacies. Further review is required before the Food and Drug Administration (FDA) decides whether to approve it for sale. That could take several months to a year, says Dr. Reisberg. Until then, your doctor cannot prescribe it. The drug has recently been approved for treating Alzheimer's in Germany and other European countries, where it sells for about $600 a month.
Further study is needed to determine how long benefits may persist, and whether the pill may work in the early stages of the illness or when combined with existing Alzheimer's drugs. "The findings may also be applicable to other degenerative nerve diseases, such as Parkinson's, and possibly even glaucoma," Dr Reisberg says.
The drug works in a new way, shielding brain cells from overexposure to a brain chemical called glutamate. Short bursts of glutamate help to lock in memories. But when levels of the substance become persistently high, as in Alzheimer's disease, brain cells die off. Memantine blocks a receptor for glutamate, shielding brain cells from its damaging effects while allowing the short pulses that foster memory and learning.
Currently available Alzheimer's drugs are aimed at slowing the destruction of acetylcholine and other chemicals in the brain that promote communication between cells. They have limited effectiveness, however, and are generally prescribed for the earlier stages of the illness.
Nearly five million Americans have Alzheimer's disease, with the number growing rapidly. Memantine offers a possible new avenue of treatment for many of these patients, as well as the almost 500,000 new cases diagnosed each year.
Results of the study were published in the April 3, 2003, issue of the esteemed New England Journal of Medicine. Copies of the article (written for doctors) and background information on the medicine can be obtained by calling the information line at Forest Laboratories, the U.S. makers of the drug, at 1-800-678-1605, extension 7301.
Copy by Toby Bilanow for www.ALZinfo.org, The Alzheimer's Information Site. Reviewed by Samuel E. Gandy, M.D., Ph.D., Chairman of the Scientific Advisory Board, Fisher Center for Alzheimer's Research Foundation.