Of all geriatric diseases, dementia is one of the most dreaded. Dementia, defined as an acquired global impairment of intellect, reason and personality, doubles in frequency every five years after age 65. In other words, twice as many people are demented at 70 than at 65. Population studies indicate that Alzheimer's disease causes 50 percent of dementias, affecting more than 4 million Americans now and an estimated 14 million by the year 2040. Vascular disorders contribute to another 20 percent of dementias. Other secondary causes include trauma, drugs, nutrient deficiencies and progressive diseases such as multiple sclerosis and Parkinson's disease.¹

While dementia occupies the extreme end of the spectrum of cognitive decline, memory loss associated with aging is often assumed to be part of the normal aging process. Baby boomers would be wise to undertake a comprehensive wellness approach to prevent and treat age-related cognitive decline, and to do so now. As discussed in the May 1996 issue of Nutrition Science News (p. 26), an effective dietary supplement to do this is a standardized extract made from the leaves of the Ginkgo biloba tree. This article is a follow-up to the last, and expands on the many studies demonstrating ginkgo's effectiveness in lessening cognitive decline.

Ginkgo Biloba Extract
According to the German Commission E Monographs, the many actions of a standardized extract of Ginkgo biloba leaves include:

* Improving the ability of tissues, particularly brain tissue, to withstand insufficient oxygen;
* Inhibiting the development of a traumatically or toxically produced brain swelling and acceleration of decongestion;
* Increasing memory performance and learning capacity;
* Improving compensation of disturbed equilibrium due to impaired blood flow to the brain and inner ear;
* Improving circulatory flow, particularly in the small vessels;
* Inactivating toxic oxygen radicals (i.e., it's a good free radical scavenger), and
* Producing a general neuroprotective effect.²

While numerous texts make reference to the ability of Ginkgo biloba extract (GBE) to improve circulation to the brain and extremities and to mop up free radicals, research also shows that GBE can directly enhance cognitive activity. Two studies with healthy volunteers used electroencephalograph (EEG) measures throughout the brain to quantify the effects of GBE on brain activity.^3,4 Single applications of 40 mg, 120 mg and 240 mg were given. The lowest dose had no effect. At the higher doses, GBE increased alpha-wave activity on par with drugs such as tacrine hydrochloride that improve cognitive function. Theta-wave activity also decreased. (Whereas alpha-wave activity is common in normal, alert people, those with dementia typically show an abnormal rise in theta or slow-wave activity.) Onset of action was rapid (30 minutes), with a peak effect at two to three hours and continued action over the five-day treatment period. The authors of both studies concluded that GBE has a "cognitive-activating profile," meaning it increases brain activity associated with alertness.

What's exciting about these results is that they confirm what many researchers have long suspected--that GBE can slow age-related cognitive decline and should help people with early-stage dementia, including Alzheimer's disease. New clinical studies support these hypotheses. These benefits look even better when you consider that standard drug therapies for early-stage dementia are expensive and often toxic to the central nervous system (CNS) and liver.

Studies in the 1980s and early 1990s demonstrated the efficacy of GBE in the treatment of memory loss, depression and disorientation associated with poor blood flow to the brain in geriatric patients.^5-8 The big breakthrough, however, came with the publication of two studies that demonstrated the efficacy of GBE for patients with either mild to moderate Alzheimer's disease or multi-infarct dementia.

The first study involved 40 hospitalized patients aged 50 to 75 years with a diagnosis of senile dementia of the Alzheimer's type (SDAT).⁹ Patients received either 240 mg of GBE (80 mg three times per day) or a placebo daily for three months. Using EEGs and a battery of tests that measured memory, reaction time, mental clarity and mood, researchers assessed patients at baseline and at one, two and three months. Compared to the placebo group, the GBE group showed significant improvement in memory and attention. Noticeable changes began as early as one month, with continued progress at two and three months.

The GBE group also demonstrated pronounced improvements in mental clarity, memory, mood and appetite. Other benefits in the GBE group included a decrease in orientation disturbances, better emotional stability, decreased anxiety and depression, and increased motivation and initiative. EEG measures showed a decrease in the theta-wave and an increase in alpha-wave activity. No side effects were reported.

In the second study, of 156 patients age 55 and up with mild to moderate Alzheimer's disease or multi-infarct dementia, researchers noted a significant improvement in two of three psychological tests for patients taking GBE during a six-month, double-blind, placebo-controlled trial.¹⁰ At 24 weeks, the GBE group also improved significantly in the tests measuring cognitive function, memory, attention and mood, with a decrease in depression. Both types of dementia responded equally well to the GBE.

In elderly patients, depression is often an early sign of cognitive decline and poor blood flow to the brain. This form of low mood is often described as "resistant" depression, meaning that it is unresponsive to standard antidepressant drugs or phytomedicines such as St.-John's-wort (Hypericum perforatum). The reason may have to do with the underlying cause. Whereas younger adults with clinical depression often have a neurotransmitter imbalance, elderly patients may be suffering from insufficient blood flow to the brain. Because GBE improves cerebral circulation, researchers wondered whether it might offset low mood in the elderly. In one study, 40 patients, aged 51 to 78 years, with a diagnosis of resistant depression received either GBE (80 mg three times daily) or placebo for eight weeks.¹¹ During the study, patients remained on their conventional antidepressant medications. By four weeks, patients treated with GBE had a significant decline in a standard measure used to test depression (Hamilton Depression Scale). By eight weeks, their scores dropped further. In addition to less depression, the GBE group also showed a significant improvement in overall cognitive function. No side effects were reported.

The German Commission E Monograph also recommends GBE for vertigo (a spinning sensation) and tinnitus (ringing in the ears). GBE has also been used to manage intermittent claudication, a condition characterized by leg pain during exercise due to poor arterial circulation. Numerous studies have found success using 120 mg of GBE daily for this indication.¹² GBE may also help patients with transient ischemic attacks, strokes and head injuries.¹³

Recommended Dosage
For preventing and treating circulation problems affecting the arms and legs, GBE, standardized to contain 6 percent terpene lactones and 24 percent ginkgo flavone glycosides, is recommended at a daily dosage of 120 to 160 mg divided into two or three doses. For CNS-related conditions (i.e., early-stage dementia, resistant depression, transient ischemic attacks and trauma), the daily dosage is 240 mg in two or three divided doses. Significant effects are often noted as early as four weeks. To make sure that the GBE is working beyond the anticipated placebo effect range, patients should initially keep taking it for six to eight weeks. Patients who are benefiting from GBE should continue the 240 mg dosage for at least six months with reduction to 120 mg upon clinical improvement.

Side effects from the standardized extract are rare. Mild gastrointestinal upset has been observed in less than 1 percent of patients in clinical studies. Some patients with poor blood flow to the brain may experience a mild, transient headache for the first one or two days of use. Although no interactions with commonly prescribed drugs are known, concomitant use with anticoagulant medication should be closely monitored. The current Commission E monograph lists no contraindications to the use of GBE during pregnancy or lactation.

In addition to ginkgo, studies have found that other supplements can help prevent or ameliorate dementia. I don't advocate that elderly patients take all of these supplements, but rather, recommend they plan their cognitive-enhancing supplement regime under the guidance of a health care professional trained in therapeutic nutrition and herbal medicine.

Donald J. Brown, N.D., is the founder and director of Natural Product Research Consultants (NPRC, Inc.) in Seattle. NPRC produces the Quarterly Review of Natural Medicine and has produced a series of condition-specific monographs examining clinical applications of natural medicine. The most current monograph covers dementia and age-related cognitive decline.

REFERENCES

1. Cummings, J.L. & Bensen, D.F. Dementia: A Clinical Approach, 2nd ed.: 2. Boston: Butterworth-Heinemann, 1992.

2. Monograph, Ginkgo biloba leaves (dry extract). Bundesanzieger, June 21, 1994.

3. Luthringer, R., d'Arbingy, P., et al. In Christen, Y., Courtis, Y., et al., eds. Effects of Ginkgo biloba Extract (EGb 761) on Aging and Age-Related Disorders: 107-18. Paris: Elsevier, 1995.

4. Itil, T.M., Eralp, E., et al. Am J Therapeutics, 3: 63-73, 1996.

5. Voberg, G. Clin Trials J, 22: 149-57, 1985.

6. Mancini, M., Agozzino, B., et al. Gaz Med Ital, 152: 69-80, 1991.

7. Kleijnen, J. & Knipschild, P. Br J Clin Pharmacol, 34: 352-58, 1992.

8. Rai, G.S., Shovlin, C., et al. Curr Med Res Opin, 12: 350-55, 1991.

9. Hofferberth, B. Human Psychopharm, 9: 215-22, 1994.

10. Kanowski, S., Herrman, W.M., et al. Pharmacopsychiatry, 29: 47-56, 1996.

11. Schubert, H. & Halma, P. Geriatr Forsch, 3: 45-53, 1993.

12. Schneider, B. Arzneim-Forsch Drug Res, 42: 428-36, 1992.

13. Monograph, Ginkgo biloba leaves, loc. cit.