Rationale

It has been proposed that green tea extract may have a beneficial impact on cognitive functioning, suggesting promising clinical

implications. However, the neural mechanisms underlying this putative cognitive enhancing effect of green tea extract still remain

unknown.

Objectives

This study investigates whether the intake of green tea extract modulates effective brain connectivity during working memory

processing and whether connectivity parameters are related to task performance.

Material and methods

Using a double-blind, counterbalanced, within-subject design, 12 healthy volunteers received a milk whey-based soft drink

containing 27.5 g of green tea extract or a milk whey-based soft drink without green tea as control substance while undergoing

functional magnetic resonance imaging. Working memory effect on effective connectivity between frontal and parietal brain

regions was evaluated using dynamic causal modeling.

Results

Green tea extract increased the working memory induced modulation of connectivity from the right superior parietal lobule to the

middle frontal gyrus. Notably, the magnitude of green tea induced increase in parieto-frontal connectivity positively correlated with

improvement in task performance.

Conclusions

Our findings provide first evidence for the putative beneficial effect of green tea on cognitive functioning, in particular, on working

memory processing at the neural system level by suggesting changes in short-term plasticity of parieto-frontal brain connections.

Modeling effective connectivity among frontal and parietal brain regions during working memory processing might help to assess

the efficacy of green tea for the treatment of cognitive impairments in psychiatric disorders such as dementia.