Editor’s note:   A new study failed to demonstrate that ginkgo biloba prevent Alzheimer’s disease in people younger than 75.   This study does not seem to be reasonably planned as the herbal industry pointed out that prevention of the disease should start earlier.   At age 75, much of the damage may have already been done.

Regardless of how ginkgo affects the risk of Alzheimer’s, we publish below a report on studies of grape-seed extract, another potential dietary supplement that may help patients with Alzheimer's.

A new study published in the Nov 21, 2008 issue of Journal of Biological Chemistry suggests that patients with Alzheimer's disease may be better off taking grape-seed extract supplements.

Epidemiological studies have found that moderate consumption of red wine rich in polyphenols were associated with reduced incidence of Alzheimer's disease, prompting some researchers to speculate that polyphenols in grape seeds may provide similar benefits.

The current study led by Ono K and colleagues from the University of California in Los Angeles provided some detailed laboratory evidence suggesting that grape seed-derived polyphenols help prevent the two predominant disease-related amyloid beta protein alloforms.

The grape-seed polyphenolic extract used in the current study called MegaNatural-AZ or MN, which is commercially available, has been tested already in another study and been found to be able to significantly attenuate AD-type cognitive deterioration and reduced cerebral amyloid deposition.

The previous study was led by Wang J and colleagues from Mount Sinai School of Medicine in New York, New York and published in the June 18 2004 issue of Journal of Neuroscience.

"In this study, we found that a naturally derived grape seed polyphenolic extract can significantly inhibit amyloid beta-protein aggregation into high-molecular-weight oligomers in vitro. When orally administered to Tg2576 mice, this polyphenolic preparation significantly attenuates AD-type cognitive deterioration coincidentally with reduced HMW soluble oligomeric Abeta in the brain. Our study suggests that grape seed-derived polyphenolics may be useful agents to prevent or treat AD (Alzheimer's)," the authors write.

In the current study, Ono and colleagues tested the effects of MN on the two amyloid beta-protein alloforms, Abeta40 and Abeta42.

They found that MN blocks Abeta fibril formation by inhibiting protofibril formation, pre-protofibrillar oligomerization, and initial coil --> alpha-helix/beta-sheet secondary structure transitions.

Protective effects were also demonstrated in assays of cytotoxicity. The researchers concluded in their report that these data suggest that grape-seed polyphenolic extract is worthy of consideration as a therapeutic agent for Alzheimer's disease.

Only a handful of studies have ever been conducted on the effects of grape-seed extract on Alzheimer's disease.   The first one was probably carried out by Li MH and colleagues in Seoul National University in South Korea.

They reported their study in the Dec 2004 issue of Annals of the New York Academy of Sciences saying that formulated polyphenol oligomers (Oligonol) derived from grape seed extracts were able to prevent Abeta-induced oxidative cell death, which they believed to have something to do with Alzheimer's.

Later, Deshane J and colleagues from University of Alabama at Birmingham Comprehensive Cancer Center reported in the Dec 29 2004 issue of the Journal of Agricultural and Food Chemistry that a grape seed extract enriched in proanthocyanidins (PA) (oligomeric polyphenols) affects 13 proteins in the brains of rats fed with the supplements. These proteins are believed to be involved in diseases like Alzheimer's.

Alzheimer's disease is an abnormal age-related brain disease afflicting an estimated 4.5 million Americans.   The disease more often starts after age 60.  Five percent of those age 65 to 74 have Alzheimer's  compared to nearly about half of those age 85 and older.

Alzheimer's disease is incurable. Those who want to reduce the risk may consider prevention measures including taking ginkgo earlier.

For more information, read http://www.nia.nih.gov/Alzheimers/Publications/adfact.htm