Ginkgo and Alzheimer's disease: little or no different from placebo.

(1) Drug treatments for Alzheimer's disease have no more than modest and transient efficacy but can cause significant adverse effects. Other treatments are therefore being explored, including plant extracts. (2) Is Ginkgo biloba (maidenhair tree) any more effective than placebo in Alzheimer's disease? To answer this question, we carried out a review of available evidence based on Prescrire's standard methodology. (3) Ginkgo biloba has been widely used for many years by people with symptoms attributed to "cerebrovascular insufficiency", despite the lack of evidence of a causal role. (4) About thirty placebo-controlled trials in patients with various types of dementia have been published, with highly inconsistent results. If these studies showed any effect on cognition, it was weak and did not last more than 6 months. (5) Cases of haemorrhage were reported, and this means that caution is needed, especially in patients at increased risk of haemorrhage, such as those on ongoing anticoagulant or antiplatelet treatment. (6) In practice, Ginkgo biloba extract appears to be little or no different from placebo in the treatment of Alzheimer's disease. Its short-term use is acceptable under some conditions, but the potential risk of bleeding must be kept in mind.