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differences between ginkgo and placebo in the proportion of participants experiencing
adverse events. A subgroup analysis including only patients diagnosed with Alzheimer’s
disease (925 patients from nine trials) also showed no consistent pattern of any benefit
associated with ginkgo.
GUIDAGE STUDY: THE 2012 GuidAge Study, complementing the NCCAM-FUNDED
GINKGO EVALUATION OF MEMORY (GEM) STUDY of the standardized ginkgo product,
EGb 761, found it INEFFECTIVE in lowering the overall incidence of dementia and
Alzheimer's disease in older people with normal cognition. 2854 participants were
randomly assigned, “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.”^24
GUIDAGE STUDY CONCLUSION: Long-term use of standardized ginkgo biloba extract in
this trial did not reduce the risk of progression to Alzheimer's disease compared with
placebo.^25
Given the inconsistent use pattern, some further analysis seems warranted. Analysis
sponsored by a supplement manufacturer showed that ginkgo might yet be shown to
protect the subgroup of long-term users: 15 out of 947 patients (1.6%) in the EGb 761
group who took ginkgo for at least four years converted to AD versus 29 out of 966
(3.0%) in the placebo group (statistically significant at p=0.03). However, the Guidage
Study Group confirmed the Evaluation of Memory (GEM) Study conclusion that ginkgo
did not prevent AD: Significantly, the manufacturer-sponsored early analysis of the