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In 1996, Kanowski et al. reported about the beneficial effects of ginkgo biloba special extract EGb 761 (240 mg/day) in outpatients with pre-senile and senile primary degenerative dementia of the Alzheimer type (DAT) and multi-infarct dementia (MID) of mild to moderate severity. The comparison of the results of this double-blind, placebo-controlled, randomized, multi-center study with other dementia studies is hampered by the fact that only the responder analysis of the per-protocol (PP) population, which was pre-specified in the protocol as confirmatory analysis, has been published in detail so far. Moreover, cognitive functioning was measured using the Syndrom-Kurztest (SKT), whereas results of other studies are based on the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-cog). Therefore, the conventional intention-to-treat (ITT) analysis of this study is provided with an estimation of ADAS-cog scores based on measured SKT scores. After 24 weeks of treatment, the ITT analysis of the SKT and estimated ADAS-cog scores revealed a mean decrease in the total score by -2.1 (95 % CI: -2.7; -1.5) points and -2.7 (95 % CI: -3.5; -1.9) points, respectively, for the EGb 761 group, which indicates an improvement in cognitive function. On the contrary, the placebo group exhibited only a minimal change of -1.0 (95 % CI: -1.6; -0.3) and -1.3 (95 % CI: -2.0; -0.4) points, respectively. The changes from baseline differed significantly between treatment groups by 1.1 (SKT) and 1.4 (estimated ADAS-cog) points, respectively (P = 0.01). The Clinical Global Impression of Change (CGI, Item 2) favored the EGb 761 group with a mean difference of 0.4 points (P = 0.007). Changes in the rating related to activities of daily living (Nürnberger-Alters-Beobachtungs-Skala, NAB) showed a favorable trend for EGb 761R. A subgroup analysis regarding patients with DAT yielded comparable results. Using a decrease of at least 4 points on the estimated ADAS-cog scores as cutoff criterion for treatment response, 35 % of EGb 761-treated patients were considered responders versus only 19 % for the placebo group (P = 0.01). The results of this ITT analysis substantiate the outcomes previously obtained with a responder analysis of the per-protocol population and confirm that EGb 761 improves cognitive function in a clinically relevant manner in patients suffering from dementia. The therapeutic effect is in line with the outcome of another EGb 761 study conducted in the U.S.
Kanowski et al. (Sat,) studied this question.