When it comes to herbal medicine, count me a skeptic. Some people swear by many herbs, but when these same herbs are objectively tested under controlled conditions, they fail spectacularly or they only show modest effects.
For example, a lady in my church is absolutely certain that Echinacea will cure your cold. However, a paper by Barrett in Phytomedicine, 2003 Jan;10(1):66-86 reviews several Echinacea trials and concludes that: “Although suggestive of modest benefit, these trials are limited both in size and in methodological quality. Hence, while there is a great deal of moderately good-quality scientific data regarding E. purpurea, effectiveness in treating illness or in enhancing human health has not yet been proven beyond a reasonable doubt.” Also the prestigious Cochrane database has examined many human trials that tested Echinacea and concluded that “Echinacea preparations tested in clinical trials differ greatly. There is some evidence that preparations based on the aerial parts of Echinacea purpurea might be effective for the early treatment of colds in adults but results are not fully consistent. Beneficial effects of other Echinacea preparations, and for preventative purposes might exist but have not been shown in independently replicated, rigorous randomized trials.” For this study, see Linde K, Barrett B, Wölkart K, Bauer R, Melchart D. Echinacea for preventing and treating the common cold. Cochrane Database Syst Rev. 2006 Jan 25;(1):CD000530,
When it comes to Ginkgo biloba extracts, the use of Ginkgo for age-related dementia has a veritable history, but the Cochrane reviews concluded: “The evidence that Ginkgo biloba has predictable and clinically significant benefit for people with dementia or cognitive impairment is inconsistent and unreliable.” See Birks J, Grimley Evans J. Ginkgo biloba for cognitive impairment and dementia. Cochrane Database Syst Rev. 2009 Jan 21;(1):CD003120. doi: 10.1002/14651858.CD003120.pub3.
Therefore, it is with some skepticism that I relate the following report to you.
Neural stem cells in the subventricular zone of the hippocampal dentate gyrus on adult mammals are responsible for learning and memory. These cells stop dividing during severe depression and dementia and expand during learning.
The natural growth of these stem cells is insufficient to replenish cells after a severe stroke or in the event of serious brain disease. Therefore finding a way to stimulate these is important from a clinical standpoint.
Professor Yuliang Wang from Weifang Medical University has used an extract of Ginkgo biloba called EGb761 to treat rats with dementia. In their hands, this materials seems to safely treat memory loss and cognitive impairment (see Zhang Z, Peng D, Zhu H, Wang X. Experimental evidence of Ginkgo biloba extract EGB as a neuroprotective agent in ischemia stroke rats. Brain Res Bull. 2012 Feb 10;87(2-3):193-8).
Wang and his co-workers took this work one step further and examined the effects of EGb761 on the proliferation of neural stem cells in the subventricular zone and dentate gyrus of rats with vascular dementia.
According to Wang and others, the extract promoted and prolonged the proliferation of neural stem cells in the subventricular zone and dentate gyrus of rats with vascular dementia. The cells continued to proliferate for four months and improved learning and memory in rats with vascular dementia.
If you do not believe it, see Wang JW and others, Neural Regeneration Research 2013; 8 (18): 1655-1662.