A:The most well-established herbal treatment for Alzheimer's disease (and, indeed, one of the few herbs that probably deserves the description "proven effective") is the ancient herb Ginkgo biloba. Ginkgo, the oldest surviving species of tree, has been traced back 300 million years.

In Europe, researchers focused on ginkgo leaf, using standardized extracts of it rather than the whole herb. By 1995, ginkgo leaf extract had become the most widely prescribed herb in Germany. Today, German family physicians generally favor it above all drug treatments for dementia.

In the past, scientists believed that dementia was caused by a reduced blood and oxygen supply to the brain. Because ginkgo appears to improve circulation, European physicians assumed that ginkgo was simply getting more blood to brain cells and thereby making them work better. However, advances in the understanding of age-related mental decline have led scientists to move away from this theory. Ginkgo is now believed to function by directly stimulating nerve cell activity and protecting nerve cells from further injury.