Twenty-two percent of the participants aged 75 years or older had MCI. Mild cognitive impairment is a heterogeneous syndrome, where the MCI amnestic-type is less frequent than the MCI multiple cognitive deficits-type. Most of the participants with MCI had comorbid conditions that may affect their cognitive functions.
Context
Ginkgo biloba is widely used for its potential effects on memory and cognition. To date, adequately powered clinical trials testing the effect of G biloba on dementia incidence are lacking.
Objective
To determine effectiveness of G biloba vs placebo in reducing the incidence of all-cause dementia and Alzheimer disease (AD) in elderly individuals with normal cognition and those with mild cognitive impairment (MCI).
Design, Setting, and Participants
Randomized, double-blind, placebo-controlled clinical trial conducted in 5 academic medical centers in the United States between 2000 and 2008 with a median follow-up of 6.1 years. Three thousand sixty-nine community volunteers aged 75 years or older with normal cognition (n=2587) or MCI (n=482) at study entry were assessed every 6 months for incident dementia.
Intervention
Twice-daily dose of 120-mg extract of G biloba (n=1545) or placebo (n=1524).
Main Outcome Measures
Incident dementia and AD determined by expert panel consensus.
Results
Five hundred twenty-three individuals developed dementia (246 receiving placebo and 277 receiving G biloba) with 92% of the dementia cases classified as possible or probable AD, or AD with evidence of vascular disease of the brain. Rates of dropout and loss to follow-up were low (6.3%), and the adverse effect profiles were similar for both groups. The overall dementia rate was 3.3 per 100 person-years in participants assigned to G biloba and 2.9 per 100 person-years in the placebo group. The hazard ratio (HR) for G biloba compared with placebo for all-cause dementia was 1.12 (95% confidence interval [CI], 0.94–1.33; P=.21) and for AD, 1.16 (95% CI, 0.97–1.39; P=.11). G biloba also had no effect on the rate of progression to dementia in participants with MCI (HR, 1.13; 95% CI, 0.85–1.50; P=.39).
Conclusions
In this study, G biloba at 120 mg twice a day was not effective in reducing either the overall incidence rate of dementia or AD incidence in elderly individuals with normal cognition or those with MCI.
In disabled older women, self-report of physician diagnosis of HF, PD, DM, cancer, stroke, and DD appears valid. In general, increasing comorbidity and age and decreasing cognition and education do not reduce validity for diseases where agreement was excellent overall.
The development of MCI is associated with measurements of cognition and depression, racial and constitutional factors, and cerebrovascular disease. Early cognitive deficits seem to be a common denominator for the 2 forms of MCI; the presence of cerebrovascular disease and the APOE epsilon4 allele is associated with the amnestic type of MCI.
Cognitive impairment and decline are associated with asymptomatic high-grade stenosis of the left internal carotid artery. The persistence of the association after adjustment for right-sided stenosis indicates that the association is not due to underlying vascular risk factors or atherosclerosis in general.
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