GINKGO BILOBA AND ALZHEIMER’S DISEASE
A few years ago I called a woman whose husband I was treating. I told her I wanted to refer him to a neurologist. “For his back?” she questioned. “No,” I answered. "I am worried about his memory." (In fact, I was worried about Alzheimer's.) After a long pause, she said, “I have been too. And I have been asking him to see a doctor about it, but he just gets angry and won’t go.” I said, “I'll say I want him to see a neurologist for a second opinion on his back. After we make the appointment, we'll call you and you can call the doctor while he's on the way home.” Our plan worked. My patient did see the neurologist, and sadly, our suspicions were confirmed. I put him on ginkgo biloba but it did not seem to slow the progression of his condition.
ALZHEIMER’S – A BRIEF REVIEW: Alzheimer’s is a degenerative brain disease. It is the most common cause of dementia (memory loss, confusion and difficulty with speech, judgment and emotions) by a wide margin. Very simplified overviews of the two mechanisms of the disease process are as follows:
1.) The first feature of the Alzeheimer's disease process causes harm outside the cells of the brain. Amyloid precursor proteins (APP) are found in the synapses of neurons. They are on the cell membranes and could be described as hair-type structures which, under normal conditions, help nerve cells grow and repair. In Alzheimer’s disease, something activates enzymes that cut these proteins like scissors cut hair. The cuttings are protein fragments are known as beta-amyloid. They begin to coalesce and form insoluble plaque which proliferates around blood vessels and nerve cells in the brain, causing compression and atrophy of vital structures.
2.) Alzheimer's disease has a second pathological process that harms the inside of nerve cells. Tau proteins normally stabilize intraneuronal structures. Something triggers their regulatory enzymes to become overactive. This changes the shape of Tau proteins which leads to the formation of neurofibrillary tangles which destroys the inside of the cell.
The result is mild memory loss progressing to significant memory loss along with other neuropsychological symptoms including confusion, learning difficulties, mood swings, personality changes and progressive cognitive dysfunction. It is a devastating disease to witness and a problem that is growing around the world.
GINKGO BILOBA
For quite a few years Ginkgo Biloba has been promoted as a natural treatment to prevent or, in most cases, retard the progression of Alzheimer’s disease. The literature supporting it has been inconsistent. Alternative practitioners in the complementary health professions tender to emphasize and gravitate toward the positive studies while traditional mainstream medicine tends to be more skeptical of smaller studies from less prestigious journals and point to the larger analyses
like the review of 36 studies comprising over 4400 people with mental function loss. In that paper, the authors could not determine if ginkgo biloba was effective although they did confirm its safety1.
GINKGO BILOBA AND MEMORY
The Ginkgo Evaluation of Memory Study was done involved over 3000 subjects with a mean age of 79 years. The National Center for Complementary and Alternative Medicine (NCCAM) and the Office of Dietary Supplements were the primary sponsors of this double-blind study. Both alternative and allopathic practitioners were anticipating the results. Subjects were given 240 mg of gingko biloba extract (120 mg b.i.d.) standardized to contain 24% gingko-specific flavone glycosides and 6% terpene lactones or a placebo in the same packaging and taken in the same manner.2 The trial ran from 2000 until 2008 with a median followup time of six years. Exclusion criteria included those with marked dementia, current use of antidepressants, low vitamin B12 levels and thyroid disease. Subjects with mild cognitive impairment based on published guidelines3 were not excluded. They comprised 15% of the 1524 placebo takers and 16.5% of the 1545 test subjects. Participants received a battery of tests at baseline and took the Modified Mini-Mental State examination and Alzheimer’s Disease Assessment Scale test every six months until 2004, and then annually along with 10 other neuropsychological tests. The results of the study are in table 1. The scores are tabulation from numerous tests done by the authors. The smaller score indicates a slower rate of decline, which is a more favorable outcome.
Table 1
Neuropsychological Test Score Decline Rates |
|||
TEST CATEGORY |
PLACEBO |
GINKGO |
MOST EFFECTIVE |
Memory |
0.041 |
0.043 |
Placebo |
Attention |
0.048 |
0.043 |
Gingko |
Visuospatial |
0.118 |
0.107 |
Gingko |
Language |
0.041 |
0.045 |
Placebo |
Executive function |
0.089 |
0.092 |
Placebo |
Cognition |
0.071 |
0.069 |
Ginkgo |
Comment:
In the largest, longest trial on Ginkgo Biloba and neurocognitive decline for the results were unimpressive to some and disappointing to others. If you have a patient, family member or friend with Alzheimer’s disease and Ginkgo helps them, keep giving it. Because of the money involved, there will probably be a pushback from those who manufacture, market and sell Ginkgo. Rather than make accusations or claim conspiracy, I hope those who profit from sales will use their profits to fund more studies to either confirm or refute the findings of this one. And, it is important to remember that failure to reduce mental decline does not mean Ginkgo will be ineffective for it's other proposed, less publicized applications.
References’:
1. Birks, J., Evans J.G, Ginkgo Biloba for Positive Impairment and Dementia. Cochran Data Base of Systemic Reviews, 2009 (1): CD003120
2. Snitz, B. E, O’Meara, E.S., Carlson, M.C., et al. Ginkgo Biloba for Preventing Cognitive Decline in Older Adults. JAMMA, 2009; 302(24): 2663-2670
3. Winblad, B., Palmer, K., Kibipelto, M., et al. Mild Cognitive Impairment: Report of International Working Group on Mild Cognitive Impairment. J Intern Med 2004; 256 (3): 240-246