Medicinal plant extracts for the treatment of dementia - A review of theirpharmacology, efficacy and tolerability

Various active compounds derived primarily from Oriental and European medic inal plants, including Ginkgo biloba, Panax ginseng, Nicotiana tobaccum, Hu perzia serrata, Galanthus nivalis and Salvia officinalis, have been assesse d for their efficacy in dementia, primarily in Alzheimer's disease. These p lants may be used individually or, particularly in traditional Chinese or A yurvedic formulations, in combination. The mechanisms of action of medicinal plant extracts in Alzheimer's disease have yet to be fully determined, but are thought to involve anticholineste rase, anti-inflammatory, antioxidant and estrogenic activity, and cholinerg ic receptor activation. Robust clinical trial data are currently scarce. Ho wever, those that are available confirm the effectiveness of G. biloba in d elaying deterioration or inducing symptomatic improvement in patients with Alzheimer's disease. In addition, the extract does not appear to be associa ted with adverse or toxic effects. The active component of G. nivalis, the selective acetylcholinesterase inhibitory alkaloid galantamine (galanthamin e), is currently commercially available in Austria and is preregistrational in a number of other countries for the symptomatic treatment of mild/moder ate Alzheimer's disease. Currently available data indicate galantamine to b e well tolerated in the long term, with a relative lack of toxicity at clin ically effective dosages. Future development tf effective novel therapeutic strategies fur dementia may benefit from the combination of conventional W estern medical science and traditional Oriental medical practices.