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Ginkgo biloba and "Mental Clarity" Ginkgo "improves mental clarity" and "sharpens mental focus" are common claims seen on packaging of this herbal supplement. The proposed mechanism of action is by "increasing the natural flow of oxygen to the brain." As a neurologist, I always wondered how this could possibly occur, especially in light of the brain’s ability to regulate its own demand for blood flow. However, after reading recent studies in the mainstream medical literature, I can appreciate how Ginkgo may truly live up to its reputation. Gingko herbal supplements are derived from the extract of the fan shaped leaves of the Ginkgo tree. It is usually sold as a standard 24% extract either as a pill or tonic. The active ingredients are not precisely known, but the therapeutic effects are thought to be related to a mixture of flavonoid and diterpene chemical compounds. These compounds are scavengers of free radicals and prevent oxidative damage to ultracellular structures. They also reduce fragility and blood loss from capillaries, the microscopic blood vessels. Ginkgo extract contains factors which inhibit platelet aggregation thereby reducing the tendency for blood clots to form in the capillary vessels. This in turn protects the brain from ischemic damage at the microvascular level (1)A recent study published in JAMA (2) reported an improvement in cognitive function among demented patients treated with Gingko compared to placebo. Patients with Alzheimer’s disease or vascular dementia were treated for 52 weeks with either Gingko (40 mg three times per day) or placebo. Cognitive function was measured by formal testing as well as by caregiver assessment . The Gingko treated patients as a group scored better in both measures than the placebo group. The degrees improvement in cognitive and social functioning, though modest, were of sufficient magnitude to be recognized by caregivers. No serious or harmful side effects were encountered. It is a well known fact that, with advancing age, microvascular ischemic changes, or "microscopic strokes", occur in the deep white matter of the brain. These changes usually appear on MRI scans as punctate lesions or "white dots" in the white matter around the ventricles of the brain. With advancing age increasing numbers of these lesions accumulate. Early in the course of this process, their effects are not apparent. However, as lesions accumulate, symptom eventually manifest as either strokes, and/or senility. By the time signs of senility are apparent, or a stroke has occurred, the brain as seen on the MRI, is filled with "white dots". Given these observations, it is understandable that early in this process, when the lesion load is light, manifestations may be subtle and attributed to "forgetfulness" or "poor concentration". If, based on its proposed mechanism of action, the therapeutic effects of Gingko reduces the extent of microvascular damage in the brain, the clinical result may well be "mental clarity". 1. Robbers JE, Tyler VE.: Tyler’s Herbs of Choice: The Therapeutic Use of Phytomedicinals, Binghamton, NY, Hawthorne Herbal Press, 1999, pp. 141-145 2. Le Bars P, et. al. Journal of the American Medical Association 1997; 298:1327-1332, Howard Chew, MD
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