1: Ginkgo and Memory
Contemp Clin Trials. 2006 Jun;27(3):238-53. Epub 2006 Apr 19.
The Ginkgo Evaluation of Memory (GEM) study: design and baseline data of a randomized trial of Ginkgo biloba extract in prevention of dementia.
The epidemic of late life dementia, prominence of use of alternative medications and supplements, and initiation of efforts to determine how to prevent dementia have led to efforts to conduct studies aimed at prevention of dementia. The GEM (Ginkgo Evaluation of Memory) study was initially designed as a 5-year, randomized double-blind, placebo-controlled trial of Ginkgo biloba, administered in a dose of 120 mg twice per day as EGb761, in the prevention of dementia (and especially Alzheimer's disease) in normal elderly or those with mild cognitive impairment. The study anticipates 8.5 years of participant follow-up. Initial power calculations based on estimates of incidence rates of dementia in the target population (age 75+) led to a 3000-person study, which was successfully recruited at four clinical sites around the United States from September 2000 to June 2002. Primary outcome is incidence of all-cause dementia; secondary outcomes include rate of cognitive and functional decline, the incidence of cardiovascular and cerebrovascular events, and mortality. Following screening to exclude participants with incident dementia at baseline, an extensive neuropsychological assessment was performed and participants were randomly assigned to treatment groups. All participants are required to have a proxy who agreed to provide an independent assessment of the functional and cognitive abilities of the participant. Assessments are repeated every 6 months. Significant decline at any visit, defined by specific changes in cognitive screening scores, leads to a repeat detailed neuropsychological battery, neurological and medical evaluation and MRI scan of the brain. The final diagnosis of dementia is achieved by a consensus panel of experts. Side effects and adverse events are tracked by computer at the central data coordinating center and unblinded data are reviewed by an independent safety monitoring board. Studies such as these are necessary for this and a variety of other potential protective agents to evaluate their effectiveness in preventing or slowing the emergence of dementia in the elderly population.
2: Ginkgo and Mild Cognitive Impairment
Aging Ment Health. 2009 Mar;13(2):171-82. doi: 10.1080/1360786080238065
Identifying mild cognitive impairment at baseline in the Ginkgo Evaluation of Memory (GEM) study.
Objectives: To identify, characterize and compare the frequency of mild cognitive impairment (MCI) subtypes at baseline in a large, late-life cohort (n = 3063) recruited into a dementia prevention trial.
Method: A retrospective, data-algorithmic approach was used to classify participants as cognitively normal or MCI with corresponding subtype (e.g. amnestic vs. non-amnestic, single domain vs. multiple domain) based on a comprehensive battery of neuropsychological test scores, with and without Clinical Dementia Rating (CDR) global score included in the algorithm.
Results: Overall, 15.7% of cases (n = 480) were classified as MCI. Amnestic MCI was characterized as unilateral memory impairment (i.e. only verbal or only visual memory impaired) or bilateral memory impairment (i.e. both verbal and visual memory impaired). All forms of amnestic MCI were almost twice as frequent as non-amnestic MCI (10.0% vs. 5.7%). Removing the CDR = 0.5 ('questionable dementia') criterion resulted in a near doubling of the overall MCI frequency to 28.1%.
Conclusion: Combining CDR and cognitive test data to classify participants as MCI resulted in overall MCI and amnestic MCI frequencies consistent with other large community-based studies, most of which relied on the 'gold standard' of individual case review and diagnostic consensus. The present data-driven approach may prove to be an effective alternative for use in future large-scale dementia prevention trials.
3: Clinical Study Reviews:
Numerous studies of ginkgo have been done for a variety of conditions. Among the most widely researched are dementia, memory impairment, intermittent claudication, and tinnitus
1. An NCCAM-funded study of the well-characterized ginkgo product EGb-761 found it ineffective in lowering the overall incidence of dementia and Alzheimer's disease in the elderly. Further analysis of the same data also found ginkgo to be ineffective in slowing cognitive decline, lowering blood pressure, or reducing the incidence of hypertension. In this clinical trial, known as the Ginkgo Evaluation of Memory study, researchers recruited more than 3,000 volunteers age 75 and over who took 240 mg of ginkgo daily. Participants were followed for an average of approximately 6 years
2. Other NCCAM-funded research includes studies of ginkgo for symptoms of multiple sclerosis, intermittent claudication, cognitive decline, sexual dysfunction due to antidepressants, insulin resistance, and short-term memory loss associated with electroconvulsive therapy for depression