A comprehensive review of 33 clinical trials yielded "promising evidence" that Ginkgo biloba can improve memory and function in people with dementia, according to Britain's Alzheimer's Society and the Cochrane Collaboration.

Ginkgo biloba is an extract from the leaves of the Ginkgo tree, sometimes called the maidenhair tree.

"The medicinal effects of Ginkgo are believed to be gained by causing blood vessels to dilate, improving blood flow to the brain, and through thinning the blood and making it less likely to clot," said Dr. James Warner, senior lecturer and consultant at Imperial College in London. "Ginkgo probably also has some anti-oxidant effects, protecting nerve cells against biological 'rusting'. All of these effects would suggest that Gingko might slow down a degenerative process."

"Ginkgo biloba appears to be safe in use with no excessive side effects compared with a placebo. Many of the early trials used unsatisfactory methods, were small, and we cannot exclude publication bias. But overall there is promising evidence of improvement in cognition and function associated with Ginkgo," said the review. "Our view is that there is need for a large trial using modern methodology to provide robust estimates of the size and mechanism of the treatment effects."

The findings have provided the go-ahead for a major new clinical trial of Ginkgo in people with early dementia who receive care from a general practitioner. The new study, run by England's Imperial College and Royal London Homeopathic Hospital, will recruit 400 people with dementia, following them over a period of six months while they receive treatment with either Ginkgo or a placebo.

Other sources: Alzheimer's Society of Britain