Ained essentially unchanged after controlling for psychotropic drug use (Table 4).DiscussionThis analysis of prospectively collected data on cognitive function over a twenty-year period has shown that the decline of the MMSE score in a population of non-demented subjects was lower in 1379592 the group of subjects who reported using EGb761H at some time than in those who did not. The difference in MMSE score at the end of the follow-up period was around five points, which can be considered an important and clinically relevant difference. The predicted MMSE score at the end of the follow-up period remained above the threshold of 24 (roughly normal cognitive function) in the group using EGb761H, which is also of clinical relevance. This effect appears to be a specific medication effect of EGb761H, since it was not observed for another nootropic medication, piracetam, prescribed for the same condition as EGb761H, whose users performed less well all along the follow-up period in the three tests studied. The latter finding suggests that the observed beneficial effect of EGb761H on cognitive decline is not an artefact of greater motivation to preserve cognitive function which encourages subjects to seek medication in general for the management of memory complaints. At first sight, these results may appear somewhat discordant with those trials such as the GEM [32] and the GuidAge [33] studies reporting no effect of the EGb761H on the risk of developing dementia, which led some authors to 11089-65-9 definitely conclude that ginkgo biloba is not effective for prevention of Alzheimer’s disease [45]. However, our results may not be so inconsistent if one considers the following issues. Firstly, it is important to emphasise that these studies relied on volunteers presenting motivation to enter clinical trials testing drug candiEffects of treatment on cognitive declineThe Table 2 shows the means and standard deviations for the three cognitive scores at each time point. The analysis of decline in cognitive scores using the linear mixed effects model with repeated measures is displayed in Table 3. As can be seen, the MMSE score declined in the `neither treatment’ group by around 0.3 points between each study visit. A significant difference in the rate of change of MMSE score 24195657 over the twenty-year follow-up period was observed in the EGb761H and piracetam treatment groups compared to the `neither treatment’ group. However, the directionGinkgo Biloba and Long-Term Cognitive DeclineFigure 1. Selection of the study sample from the PAQUID cohort. doi:10.1371/journal.pone.0052755.gdates against memory decline. Such selection bias may have led to enroll participants particularly concerned about their memory problems for potentially different reasons. Supporting this issue is the particularly high rate of conversion to dementia in the GEM study where more than 17 of the participants developed dementia within the relatively short study follow-up, suggesting that a large 3PO site proportion of participants were relatively advanced in the pre-clinical phase of dementia. The opposite seemed to occur in the GuidAge study conducted in this case in elderly people with memory complaints where the incidence of dementia was spectacularly low (actually less than half the expected value). This healthy participant effect has been noted in most dementia prevention trials and probably occurs because people who are more likely to volunteer for intervention trials might be already engaged in risk-reducti.Ained essentially unchanged after controlling for psychotropic drug use (Table 4).DiscussionThis analysis of prospectively collected data on cognitive function over a twenty-year period has shown that the decline of the MMSE score in a population of non-demented subjects was lower in 1379592 the group of subjects who reported using EGb761H at some time than in those who did not. The difference in MMSE score at the end of the follow-up period was around five points, which can be considered an important and clinically relevant difference. The predicted MMSE score at the end of the follow-up period remained above the threshold of 24 (roughly normal cognitive function) in the group using EGb761H, which is also of clinical relevance. This effect appears to be a specific medication effect of EGb761H, since it was not observed for another nootropic medication, piracetam, prescribed for the same condition as EGb761H, whose users performed less well all along the follow-up period in the three tests studied. The latter finding suggests that the observed beneficial effect of EGb761H on cognitive decline is not an artefact of greater motivation to preserve cognitive function which encourages subjects to seek medication in general for the management of memory complaints. At first sight, these results may appear somewhat discordant with those trials such as the GEM [32] and the GuidAge [33] studies reporting no effect of the EGb761H on the risk of developing dementia, which led some authors to definitely conclude that ginkgo biloba is not effective for prevention of Alzheimer’s disease [45]. However, our results may not be so inconsistent if one considers the following issues. Firstly, it is important to emphasise that these studies relied on volunteers presenting motivation to enter clinical trials testing drug candiEffects of treatment on cognitive declineThe Table 2 shows the means and standard deviations for the three cognitive scores at each time point. The analysis of decline in cognitive scores using the linear mixed effects model with repeated measures is displayed in Table 3. As can be seen, the MMSE score declined in the `neither treatment’ group by around 0.3 points between each study visit. A significant difference in the rate of change of MMSE score 24195657 over the twenty-year follow-up period was observed in the EGb761H and piracetam treatment groups compared to the `neither treatment’ group. However, the directionGinkgo Biloba and Long-Term Cognitive DeclineFigure 1. Selection of the study sample from the PAQUID cohort. doi:10.1371/journal.pone.0052755.gdates against memory decline. Such selection bias may have led to enroll participants particularly concerned about their memory problems for potentially different reasons. Supporting this issue is the particularly high rate of conversion to dementia in the GEM study where more than 17 of the participants developed dementia within the relatively short study follow-up, suggesting that a large proportion of participants were relatively advanced in the pre-clinical phase of dementia. The opposite seemed to occur in the GuidAge study conducted in this case in elderly people with memory complaints where the incidence of dementia was spectacularly low (actually less than half the expected value). This healthy participant effect has been noted in most dementia prevention trials and probably occurs because people who are more likely to volunteer for intervention trials might be already engaged in risk-reducti.
