Grape Seed Extract May Lessen Cognitive Decline Associated with Alzheimer's Disease

A compound found in grape seed extract has been found to reduce plaque formation resulting cognitive impairment in an animal model of Alzheimer's disease.

The study was published in the June 18, 2008, issue of The Journal of Neuroscience. Lead study author Giulio Pasinetti, M.D., Ph.D., from the Mount Sinai School of Medicine (New York, NY, USA) and colleagues discovered that grape seed extract prevents amyloid beta accumulation in cells, suggesting it may block the formation of plaques. In Alzheimer's disease, amyloid beta accumulates to form toxic plaques that disrupt normal brain function.

The researchers evaluated a grape seed polyphenolic extract product sold as MegaNatural-AZ, produced by Polyphenolics (Madera, CA, USA), which in part supported the study. Polyphenolic compounds are antioxidants naturally found in wine, tea, chocolate, and in some vegetables and fruits. To determine whether the extract could mitigate the effects of Alzheimer's disease, the researchers used mice genetically modified to develop a condition similar to Alzheimer's. They exposed pre-symptomatic "Alzheimer's mice” to the extract or placebo daily for five months. The daily dose of the polyphenolic extract was equivalent to the average amount of polyphenolics consumed by an individual on a daily basis.

After five months, Alzheimer's mice were at an age at which they normally develop signs of the disease. However, the extract exposure reduced amyloid beta accumulation and plaque formation in brains of Alzheimer's mice as well as reducing cognitive decline in that compared to placebo, extract-exposed Alzheimer's mice showed improved spatial memory. These data suggest that before symptoms begin, the grape seed extract may prevent or postpone plaque formation and slow cognitive deterioration associated with Alzheimer's disease.

Moderate consumption of red wine--approximately one glass for women and two glasses for men, according to the U.S. Food and Drug Administration--and its constituent grape compounds has reported health benefits, especially for cardiovascular function. Dr. Pasinetti previously found that red wine reduced cognitive decline in mice genetically modified to develop Alzheimer's disease. In subsequent research, Dr. Pasinetti and colleagues have attempted to isolate which of the nearly 5,000 molecules contained in red wine are important in disease prevention. "Our intent is to develop a highly tolerable, nontoxic, orally available treatment for the prevention and treatment of Alzheimer's dementia,” Dr. Pasinetti said.

Chemical analysis showed that the major polyphenol components in the study's grape seed extract product are catechin and epicatechin, which are abundant in tea and cocoa. These components differ from resveratrol, a polyphenol that has been reported to reduce amyloid beta secretion in cells and generally increase lifespan by mimicking caloric restriction. Resveratrol appears to be effective only at extremely high doses, which may limit its use in humans. In contrast, the catechins in the extract product evaluated appear to be effective at much lower doses.

Karen Hsiao Ashe, M.D., Ph.D., from the University of Minnesota (Minneapolis, USA) and the Minneapolis VA Medical Center, another specialist unaffiliated with the study, cautioned that additional research must be completed before these findings translate to a human population. "Unanswered questions pertaining to the polyphenolic extract's use in humans to prevent Alzheimer's disease include: when to start taking it, for how long, how much to take, and most importantly, how does a person know if it is helping to prevent the aggregation of amyloid beta protein in the brain? These questions must be answered before polyphenolics can be recommended as a preventive measure for Alzheimer's disease,” Dr. Ashe said.


Related Links:
Mount Sinai School of Medicine
Polyphenolics