Clinical improvement of memory and other cognitive functions by Ginkgo biloba: review of relevant literature.

Ginkgo biloba is a plant extract used to alleviate symptoms associated with cognitive deficits, e.g., decreased memory performance, lack of concentration, decreased alertness, tinnitus, and dizziness. Pharmacologic studies have shown that the therapeutic effect of ginkgo is based on several active constituents with vasoactive and free radical-scavenging properties. The use of ginkgo extract in either dementias of the Alzheimer or multi-infarct type or in the case of cerebral insufficiency, a symptom complex related to age-dependent impairment of cerebral circulation, is based mainly on positive results from good-quality placebo-controlled studies that enrolled approximately 1,200 patients with criteria established by International Classification of Diseases (9th and 10th revisions, ICD-9 and ICD-10) or the 3rd revision of the Diagnostic and Statistical Manual (DSM-III-R) (uncomplicated dementia). Effect on cognitive symptoms was within the range of a 25% reduction. Memory, concentration, and alertness were the first symptoms to be relieved, with tinnitus and dizziness improving somewhat later. A minimum of 4 to 6 weeks were needed before a pronounced effect could be expected. The pharmacologic advantage of ginkgo seems to be a very tolerable side-effect profile, with a side-effect frequency at the placebo level.