Sunday Nov 17, 2013 (foodconsumer.org) -- Antioxidants may help prevent or treat Alzheimer's disease, according to some recent studies.  Evidence suggests that high intake of vitamin E in the form of alpha tocopherol and vitamin C may help prevent Alzheimer's disease and Ginkgo biloba can help improve cognitive function in patients with Alzheimer's disease of  moderate severity.

Antioxidant therapy is based on the hypothesis that Alzheimer's disease may be caused by oxidative stress or get worsened by oxidative stress.   It's been quite for some time now that many people have believed that Alzheimer's disease is caused by extracellular beta-amyloid (Aβ) deposits.  But many scientists believe the disease may be caused possibly by oxidative stress, which occurs commonly in everyone, but particularly in Alzheimer's patients or those with inadequate intake of antioxidants or a pathological antioxidative defense system which allows free radicals to freely attack cells and tissues causing all sorts of cellular abnormalities.

Oxidative Stress hypothesis for Alzheimer's Disease

William R. Markesberya at University of Kentucky in Lexington, KY, USA published a review in 1997 in the journal Free Radical Biology and Medicine which explains the oxidative stress hypothesis.  He says the brain of an Alzheimer's patient is under increased oxidative stress and this may play a role in the pathogenesis of neurodegeneration and cell death leading to the development of Alzheimer's disease.

Dr. Marjesberya offers multiple observations of many signs of increased stress to support the theory including increased toxic metal ions such as iron that can catalyze lipid peroxidation; increased lipid peroxidation and decreased polyunsaturated fatty acids; increased protein and DNA oxidation, diminished energy metabolism and decreased cytochrome c oxidase; increased oxidation products like malndialdehyde, carbonyls, peroxynitrite, heme oxygenase-1 and SOD-1 and  advanced glycation end products; and capability of amyloid beta peptide per se to promote the generation of free radicals.  Antioxidants can help offset the detrimental effect from these substances, which would otherwise cause damage to cells and tissues in the brain.

The injured tissue in Alzheimer's disease can induce reactive oxygen species, which triggers a series of reactions increasing the oxidative stress, the author explains.  So it remains unknown whether these abnormalities are the cause for or result from Alzheimer's disease.  Regardless, the increased oxidative stress is damaging and the author suggests that therapeutics should be developed to remove ROS or prevent their formation in the first place.

Some scientists have tested this hypothesis.   Mary Sano and colleagues conducted a double-blind, placebo-controlled, randomized, multicenter trial of patients with Alzheimer's disease of moderate severity. In the trial, 341 patients received one of the four treatments, a selective monoamine oxidase inhibitor (selegiline,10 mg a day), alpha-tocopherol (a vitamin E, 2000 IU a day), both selegiline and alpha-tocopherol, or placebo for a period of two years. All patients were evaluated at baseline and at the end of the study using the Mini-Mental State Examination.

The study published in The New England Journal of Medicine treatment with selegiline (A drug indicated to treat Parkinson's disease and senile dementia) or alpha-tocopherol (a form of vitamin E) slow the progression of Alzheimer's disease.

The protective effect of vitamin E has been supported by epidemiologic evidence.  Another study in Free Radical Biology and Medicine suggests that only vitamin E may have the protective effect against the development of Alzheimer's disease.   The study shows that those who had high intake of vitamin E were less likely to develop Alzheimer's disease than those who had low intake.

Another study led by Marianne J. Engelhart, MD, MSc from Erasmus Medical Center in Rotterdam, the Netherlands and colleagues has also found both vitamin E and vitamin C may help prevent Alzheimer's disease.  The study published in JAMA shows individuals who had high intake of vitamin C and vitamin E were 18% less likely to develop Alzheimer's disease.

Another herbal medicine that has been tested is Ginkgo biloba.  A review of four studies in JAMA Neurology shows that Alzheimer's patients receiving 120 to 240 mg of G biloba extract for 3 to 6 months experienced a small yet significant improvement on cognitive function.  The dietary supplement was not found associated with any significant adverse effects in formal trials but except that two out of 212 patients suffered bleeding complications.

The review was authored by Barry S. Oken, MD from Oregon Health Sciences University in Portland, Oregon.

Both antioxidants ginkgo biloba and alpha tocopherol (vitamin E) are available as dietary supplements on the Internet and local health stores.   Selegiline (Anipryl, L-deprenyl, Eldepryl, Emsam, Zelapar) is a drug indicated to treat early-stage Parkinson's disease, depression and senile dementia.

Antioxidants are very important to the maintenance of everyone's health.  Aging starts when a person is born and it is a process of oxidation.  If you can stop or slow the oxidation process, you live forever or longer.  Antioxidants may not be perfect enough to stop aging completely, but they can slow the aging process.   Vitamin C and vitamin E are the most commonly used antioxidants, cheap enough that everyone afford to buy and effective enough that everyone should use.  Not just for Alzheimer's disease. (David Liu, PHD)