Neural Effects of Green Tea Extract on Dorsolateral Prefrontal Cortex

Overview

Green tea is being recognized as a beverage with potential benefits for human health and on cognitive function. In vitro and in vivo studies provide preliminary evidence that green tea intake may play a positive role in improving effects on cognitive functions. The investigators aim to examine the neural effects of green tea extract on brain activation in humans.

As functional neuroimaging provides a means of examining how green tea extract acts on the brain, we used functional magnetic resonance imaging (fMRI) to study healthy volunteers while they performed a working memory task following intra-gastric administration of either 250 ml or 500 ml Rivella green® (RG), a milk whey based green tea extract containing soft drink, or Rivella blue® (RB), a milk whey based soft drink without green tea extract as sham condition in a double-blind, controlled design. Based on the literature on pharmacological and behavioural effects of green tea, we hypothesized - a priori - that green tea extract would subtly modulate the engagement of the dorsolateral prefrontal cortex (DLPFC), a brain region critically involved in many cognitive functions such as working memory processing. A double-blind, controlled, within-subject study with counterbalanced order of substance administration using an established protocol (6-8) was conducted over 4 sessions (250 ml or 500 ml Rivella green® (including green tea extract; RG), 250 or 500 ml Rivella blue® (RB). Each participant was scanned four times with a one-week interval between scans. The order of substance administration across sessions was counterbalanced across subjects, such that equal numbers followed each substance sequence.

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