The American population is an aging society. It is estimated that at least 7 percent of Americans over age 65 will be affected by Alzheimer's disease by the year 2020, with the number afflicted climbing to 15 percent by 2050. But, while declining mental functioning is often explained as one of those "signs of aging," the condition is most often due to impaired blood flow to the brain and oxidative stress and not simply the result of advancing in years.

One of the most promising answers for the prevention and treatment of Alzheimer's and other mental impairments may be found in the leaf of Ginkgo biloba, the oldest tree species surviving today.

Numerous European studies have repeatedly shown that ginkgo extract improves blood flow to the brain, the transmission of nerve signals, and the utilization of glucose by brain cells.

Because environmental factors (such as toxins and metals) are also believed to play a role in the development of Alzheimer's, ginkgo is also valued for its antioxidative properties. In vitro (test-tube) studies demonstrate that ginkgo protects neuronal cell membranes from free-radical damage.

Last year, the Journal of the American Medical Association published a randomized, double-blind, placebo-controlled study on the efficacy of a particular extract of ginkgo popular in Europe.

At the end of the 52-week study, researchers at the New York Institute for Medical Research concluded that "[Ginkgo] was safe and appears capable of stabilizing and, in a substantial number of cases, improving the cognitive performance and the social functioning of demented patients for six months to one year."

Other notable nutrients

Another feature of Alzheimer's is the reduction of neurotransmission, due primarily to the decrease in the production of acetylcholine, the key component of which is choline, an amino acid.

Acetyl-L-carnitine, commonly referred to as simply carnitine, is a marriage of the amino acids, lysine and methionine. Several studies on Alzheimer's patients in the early 1990s showed decreased cognitive deterioration in those who supplemented with carnitine.

Several studies have also suggested that there may be a connection between antioxidant levels and mental dementia, including Alzheimer's (see "Memory Enhancement" feature, p. 58).

Other considerations

* Reduce stress and exposure to environmental toxins, especially heavy metals, such as aluminum.

* Eat a low-fat diet.

* There is a high incidence of thyroid dysfunction in Alzheimer's patients. any thyroid abnormalities should be discussed with your health-care practitioner.

REFERENCES

"Geriatrics: Ginkgo and Alzheimer's," The Integrative Medicine Consult 1 (1), December 1998.

"Improving Mental Function with Ginkgo Biloba," Health Media Communications Herbal Report 1(3), 1994.

Evans, D.A., et al. "Estimated Prevalence of Alzheimer's Disease in the U.S.," Millbank Quarterly 68:267, 1990.

La Bars, P.L., et al. "A placebo-controlled, double-blind, randomized trial of an extract of Ginkgo biloba for dementia," Journal of the American Medical Association 278(16):1327-1332, October 1997.

Maurer, K., et al. "Clinical efficacy of Ginkgo Biloba special extract Egb 761 in dementia of the Alzheimer type," Journal of Psychiatric Research 31(6):645-655, November 1997.

Oken, B.S., et al. "The Efficacy of Ginkgo biloba on Cognitive Function in Alzheimer's Disease," Archives of Neurology 55(11):1409-15, November 1998.

Pettegrew, J.W., et al. "Clinical and Neurochemical Effects of Acetyl-L-Carnitine in Alzheimer's Disease," Neurobiology of Aging 16:1, 1995.

Stoll, S., et al. "Ginkgo biloba extract (Egb 761) independently improves changes in passive avoidance learning and brain membrane fluidity in the aging mouse," Pharmacopsychiatry 29(4):144-9, July 1996.