Memantine, either alone or in combination with one of the cholinesterase inhibitors, is used for patients with moderate to severe Alzheimer's disease. Research shows that memantine helps slow the progression of memory loss and other cognitive symptoms for a period of time. A study published in the Journal of the American Medical Association in 2004 compared a group of Alzheimer's disease patients taking donepezil plus memantine with another group, taking donepezil plus a placebo. People taking both medications for six months exhibited a significantly slower pace of decline in cognitive functions. A similar finding was reported with respect to activities of daily living, which refer to bathing, dressing, and other aspects of personal care. Although patients in both groups declined over the six-month study, the decline was steeper in the donepezil plus placebo group.
Our clinical experience with memantine is similar to what we see with the cholinesterase inhibitors. Specifically, memantine appears to temporarily slow symptom progression but has no effect on the underlying disease process and does not alter the overall outcome of Alzheimer's disease.
Ginkgo Biloba. Several small studies have found that an extract from the nuts and leaves of the ginkgo biloba tree is somewhat beneficial to people with moderate to severe Alzheimer's disease— comparable to the benefits from vitamin E and the memory drugs. The mechanism of action of the gingko extract, known as EGb 761, is believed to relate to its antioxidant properties. There's some evidence that ginkgo might help prevent the formation of beta-amyloid in the brain, a key pathological feature and the possible cause of Alzheimer's disease.
Herbal supplements containing ginkgo are sold over the counter and marketed widely as memory enhancers. However, a 2002 study with cognitively normal elderly individuals failed to demonstrate a benefit on multiple measures of memory function. A larger, multicenter study is ongoing that uses higher doses of EGb 761 with cognitively normal people.
As is the case with any of the herbal remedies and other nutraceuticals (food supplements thought to have medicinal prop erties), I caution my patients and their families that because herbal supplements aren't subject to FDA scrutiny, there's no way to know the exact content, composition, or purity of the product they are buying. Because findings from clinical trials of these compounds are based on precise quantities of active ingredients, they might not pertain to you if you happen to purchase a product with a different composition. Furthermore, information used to substantiate claims of efficacy in the marketing of these substances is rarely based on the same caliber of rigorous scientific methodology required by the FDA.
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