Abstract
Evidence suggests that flavonoid-rich foods are capable of inducing improvements in memory and cognition in animals and humans. However, there is a lack of clarity concerning whether flavonoids are the causal agents in inducing such behavioral responses. Here we show that supplementation with pure anthocyanins or pure flavanols for 6 weeks, at levels similar to that found in blueberry (2% w/w), results in an enhancement of spatial memory in 18 month old rats. Pure flavanols and pure anthocyanins were observed to induce significant improvements in spatial working memory (p = 0.002 and p = 0.006 respectively), to a similar extent to that following blueberry supplementation (p = 0.002). These behavioral changes were paralleled by increases in hippocampal brain-derived neurotrophic factor (R = 0.46, p<0.01), suggesting a common mechanism for the enhancement of memory. However, unlike protein levels of BDNF, the regional enhancement of BDNF mRNA expression in the hippocampus appeared to be predominantly enhanced by anthocyanins. Our data support the claim that flavonoids are likely causal agents in mediating the cognitive effects of flavonoid-rich foods.
Highlights
Phytochemical–rich foods, those rich in flavonoids, have been shown to be effective in reversing age-related deficits in memory and learning [1,2,3,4,5,6]
Flavonoid-rich foods such as blueberry, green tea and Gingko biloba have been shown to be highly effective at reversing agerelated deficits in spatial memory and in the enhancement of different aspects of synaptic plasticity, [19,32,61,62,63], a process severely affected by ageing [64,65]
We have previously shown that intervention with a 2% (w/w) blueberry diet resulted in significant improvements in spatial working memory that were mediated through the activation of the ERKCREB-brain-derived neurotrophic factor (BDNF) pathway, a pivotal pathway for the control of synaptic plasticity [23]
Summary
Phytochemical–rich foods, those rich in flavonoids, have been shown to be effective in reversing age-related deficits in memory and learning [1,2,3,4,5,6]. Studies using Camellia sinensis (tea) [7,8,9,10,11,12], Gingko Biloba [13,14,15], Theobroma cacao (cocoa) [16,17,18] and Vaccinium spp (blueberry) [19,20,21,22,23] have demonstrated beneficial effects on memory and learning in both humans and animal models Whilst these studies clearly demonstrate the efficacy of flavonoid-rich foods in promoting cognitive performance, they fall short of providing evidence that flavonoids themselves are the causal agents in driving beneficial effects on memory, learning and neuro-cognitive performance. Declines in hippocampal BDNF levels occur during aging [41,42,43] and appear to negatively impact on memory performance [44], whilst both exercise and diet have been shown to influence BDNF expression in the hippocampus [45,46]
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