There are 122 products whose name containsGinkgo bilobalisted on the Australian Register of Therapeutic Goods (ARTG). It is one of the commonest herbal medicines taken to prevent or treat cognitive impairment. Claims include, 'helps to improve blood flow to the brain' and 'improves memory and cognitive function'. There is some evidence that taking ginkgo leaf extract orally modestly improves symptoms of Alzheimer's, vascular, or mixed dementias, but this comes from poor quality studies.4
A study, funded by the US National Center for Complementary and Alternative Medicine, of the well-characterised ginkgo product EGb-761 found it ineffective in lowering the overall incidence of dementia and Alzheimer's disease in the elderly. Further analysis also found ginkgo to be ineffective in slowing cognitive decline. This trial recruited more than 3000 volunteers aged 75 and over who took 240 mg of ginkgo daily, and followed them for around six years.5,6Some smaller studies for memory enhancement have had promising results, but a trial sponsored by the US National Institute on Aging of more than 200 healthy adults over age 60 found that ginkgo taken for six weeks did not improve memory.7
A recent press release reports that the IPSEN GuidAge study, involving 2854 participants aged 70 years or older complaining of memory problems, showed a statistically significant decrease in progression to Alzheimer's disease. The study authors conclude that the difference between their results and those of the earlier US study is due to differences in compliance.8At this stage the results should be treated with caution as they have not yet appeared in a peer-reviewed publication.
Adverse effects of ginkgo can include headache, nausea, gastrointestinal upset, diarrhoea, dizziness, or allergic skin reactions. Severe allergic reactions have occasionally been reported. There are case reports suggesting that ginkgo can increase the risk of bleeding.9It is therefore recommended that patients be cautioned if they take aspirin, warfarin or other antiplatelet or anticoagulant drugs, have bleeding disorders, or are expecting to have surgical or dental procedures.4