Preventing Age-Related Cognitive DeclineApril 2005
By Laurie Barclay, MD
Ginkgo, Ginger, and Aspirin Improve Brain Circulation
Extract of ginkgo biloba, derived from the oldest living species of tree on Earth, is a potent antioxidant53 that helps to counteract age-related changes in blood flow to the brain.54 By dilating and toning blood vessels, interfering with platelet activity to decrease blood clotting, and preventing oxidative damage to mitochondria and nerve cells,54 ginkgo enhances brain activity and energy metabolism,55 and decreases symptoms of depression and memory impairment.56
Ginkgo may be helpful in mild to moderately severe cognitive impairment associated with early Alzheimer’s disease or vascular dementia, according to a study of 202 patients reported in the Journal of the American Medical Association. During one year of treatment, patients receiving ginkgo maintained cognitive function and improved slightly in social functioning, while the placebo group deteriorated in both areas.57
In a review of 40 clinical studies using ginkgo for cerebral vascular insufficiency and for age-related dementia, nearly all trials showed improvements relative to placebo in memory impairment, confusion, fatigue, anxiety, and other symptoms.58 Another review also showed promising benefits in cognitive symptoms without serious side effects in some studies, suggesting the need for a larger, well-designed trial.59
Based on European studies, Germany has approved ginkgo biloba extract for treatment of Alzheimer’s disease and other dementias. In a placebo-controlled study,20 outpatients with mild to moderate Alzheimer’s had significant improvement in attention and memory performance after three months of treatment.60
One study showed no difference in memory scores or perceptions of improvement in cognitive function in healthy adults after six weeks of supplementing with ginkgo,61 whereas another study showed improvements with similar doses.62 A placebo-controlled study in 60 healthy volunteers showed significant improvements after 30 days of ginkgo treatment in speed of information processing, working memory, and executive processing.63 Ginkgo may be most beneficial for short-term memory in healthy adults if given as a single dose of 120 mg rather than as 40 mg three times daily.64
A German study investigated how combining ginkgo and ginger affects learning, memory, and brain oxidative stress in aged rats.65 Like ginkgo, ginger has traditionally been used by herbalists as a circulatory tonic. The investigators found that the ginkgo and ginger combination significantly reduced two indicators of oxidative stress in the brains of aged rats. Additionally, the ginkgo and ginger supplement helped to facilitate spatial learning in the animals.
Low-dose acetylsalicylic acid, or aspirin, acts as a mild blood thinner and lowers the risk of vascular events in humans. Increasing evidence suggests aspirin may also reduce the rate of cognitive decline in the elderly.66 A large study of aspirin’s ability to prevent vascular dementia in the elderly is currently underway in Australia.
Other Nutrients Show Promise
In a mouse model of brain aging, green tea extract prevented both impairments in working memory and shrinking and oxidative DNA damage to brain regions involved in memory.67 An animal model of vascular injury to the brain showed a neuroprotective effect of antioxidants that included rutin, selenium, and garlic oil.68 Aged garlic extract contains phytochemicals that prevent oxidative damage, and has shown the ability to increase cognitive function, memory, and longevity in mouse models of aging.69
Chromium improves control of blood sugar. By increasing insulin-receptor activity within the hypothalamus, a vital center for brain control, it may rejuvenate the aging brain.70 In animal studies, chromium supplements increase activity of nerve chemicals involved in controlling moods, suggesting a possible antidepressant effect.71
Bioflavonoids are a diverse group of plant-derived compounds that exert myriad effects in the body. Quercetin, a bioflavonoid with strong antioxidant properties, is found in a variety of fruits and vegetables. In a study involving mice, quercetin significantly reversed age-related cognitive decline.72 Additionally, quercetin reversed increased markers of oxidative stress and the decline of the crucial antioxidant glutathione in the forebrain, two other age-associated changes.
North American ginseng contains numerous bioactive compounds that exert many beneficial effects. One of the ginsenoside compounds from North American ginseng has been found to prevent memory deficits in rats.73 This compound facilitates the release of the neurotransmitter acetylcholine from the hippocampus, an area of the brain involved in memory and mood.
As science advances our understanding of brain aging, we have discovered many promising paths to preserving cognition well into chronological old age. Lessons learned from animal studies suggest how nutrients may best be combined to prevent age-related cognitive decline.
Free radicals are a significant culprit, interfering with energy metabolism, blood flow, and nerve structure and function. Mitochondrial energy boosters, vitamins, hormones, and other antioxidants are effective weapons in the war against oxidative stress, safely enhancing energy production and blood flow, suppressing inflammation, maintaining the structural integrity of nerve cell components, and facilitating neuronal activity.
Because these antioxidants are involved in vital functions in virtually all organ systems, supplementation to prevent age-related cognitive decline may also help protect against other age-related conditions. Nutrients have different mechanisms of action, so combining them may increase their benefits beyond that expected when each is used individually. Some physicians can offer specific advice about potential interactions of these supplements with prescription medications such as Coumadin®.
Thanks to this nutritional armamentarium, there is reason to hope that age-related cognitive decline need not be an inevitable consequence of aging. With further research, application of these strategies to early Alzheimer’s and other dementias might ultimately help reduce the toll of these dreaded and increasingly common diseases.