Ginkgo Biloba and the Prevention of Alzheimer's Disease

The American population is an aging society. It is estimated that at least 7% of Americans over age 65 will be affected by Alzheimer’s disease by the year 2020, with the rate of occurrence climbing to 15% by 2050. But, while declining mental functioning is often described as the “signs of aging,” the condition is most often due to impaired blood flow to the brain and oxidative stress and not simply the reward for advancing in years.

There are many theories as to the cause of Alzheimer’s, but certain contributing factors are now widely recognized. Genetically, Alzheimer’s is related to mutations of chromosomes 1, 14 and 21. Abnormalities of chromosome 21 (which causes Down syndrome) affects amyloid precursor protein levels and leads to increased deposits of beta-amyloid, the substance responsible for atherosclerotic plaque formation in the brain. In effect, brain cells are cut off from oxygen and nutrients and soon form tangles of dead nerve fibers. Since the brain requires about 20% of the body’s total oxygen supply, it becomes clear how vital proper cerebral vascular function is in maintaining mental alertness.

One of the most promising answers to the prevention and treatment of Alzheimer’s may be found in the leaf of the Gingko, the oldest of tree species surviving today. Numerous European studies have repeatedly shown that gingko biloba extract improves blood flow to the brain, the transmission of nerve signals and the utilization of glucose by brain cells. Because environmental factors are also believed to play a role in the development of Alzheimer’s (such as toxins and metals), ginkgo is also valued for its antioxidant properties. In vitro studies demonstrate that gingko protects neuronal cell membranes from free radical damage.

The Journal of the American Medical Association published a randomized, double-blind, placebo-controlled study on the efficacy of a particular extract of gingko biloba popular in Europe: EGb 761. At the end of the 52 week study, researchers at the New York Institute for Medical Research concluded that, “EGb 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 6 months to 1 year.”

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. Unforunately, supplementation with choline has had poor results in retarding the progression of Alzheimer’s. But, another combination of amino acids has shown positive results. Acetyl-L-carnitine, commonly referred to as simply carnitine, is a duo of amino acids called lysine and methionine. Several studies on Alzheimer’s patients in the early 1990’s evidenced decreased cognitive deterioration in those supplemented with carnitine.

Several studies have suggested that there may be a correlation between antioxidant levels and mental dementia, including Alzheimer’s. Recent studies in Austria and Switzerland have indicated that supplementation of beta-carotenes and vitamin E can improve memory and cognitive functioning in people aged 65 or more. Another recent study conducted at the USDA Human Nutrition Research Center on Aging reported that dopamine release (essential for the transmission of nerve signals) was four times greater in aging rats supplemented with antioxidant-rich extracts of strawberries, spinach and vitamin E than the control group. Overall, the rats fed the antioxidant formula demonstrated the least age-related cognitive deficiency.

Other Considerations:

- Adequate intake of supplemental antioxidants: Vitamins E, B12 and C, CoQ10, zinc and selenium.

- 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. Discuss any thyroid abnormalities with your physician.