Background:
Prevention strategies are urgently
needed to tackle the growing burden of Alzheimer's disease. We aimed
to assess efficacy of long-term use of standardised ginkgo biloba
extract for the reduction of incidence of Alzheimer's disease in
elderly adults with memory complaints.
Methods:
In the randomised, parallel-group,
double-blind, placebo-controlled GuidAge clinical trial, we enrolled
adults aged 70 years or older who spontaneously reported memory
complaints to their primary-care physician in France. We randomly
allocated participants in a 1:1 ratio according to a
computer-generated sequence to a twice per day dose of 120 mg
standardised ginkgo biloba extract (EGb761) or matched placebo.
Participants and study investigators and personnel were masked to
study group assignment. Participants were followed-up for 5 years by
primary-care physicians and in expert memory centres. The primary
outcome was conversion to probable Alzheimer's disease in
participants who received at least one dose of study drug or placebo,
compared by use of the log-rank test. This study is registered with
ClinicalTrials.gov, number NCT00276510.
Findings:
Between March, 2002, and November,
2004, we enrolled and randomly allocated 2854 participants, of whom
1406 received at least one dose of ginkgo biloba extract and 1414
received at least one dose of placebo. By 5 years, 61 participants in
the ginkgo group had been diagnosed with probable Alzheimer's disease
(1·2 cases per 100 person-years) compared with 73 participants in
the placebo group (1·4 cases per 100 person-years; hazard ratio [HR]
0·84, 95% CI 0·60—1·18; p=0·306), but the risk was not
proportional over time. Incidence of adverse events was much the same
between groups. 76 participants in the ginkgo group died compared
with 82 participants in the placebo group (0·94, 0·69—1·28;
p=0·68). 65 participants in the ginkgo group had a stroke compared
with 60 participants in the placebo group (risk ratio 1·12, 95% CI
0·77—1·63; p=0·57). Incidence of other haemorrhagic or
cardiovascular events also did not differ between groups.
Interpretation:
Long-term use of standardised ginkgo
biloba extract in this trial did not reduce the risk of progression
to Alzheimer's disease compared with placebo.
The Lancet Neurology, Volume 11, Issue
10, Pages 851 - 859, October 2012
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