Researchers have reporting first evidence that green tea extract enhances the cognitive functions, in particular the working memory.

In the new study, the researcher teams of Prof. Christoph Beglinger from the University Hospital of Basel and Prof. Stefan Borgwardt from the Psychiatric University Clinics found that green tea extract increases the brain's effective connectivity, meaning the causal influence that one brain area exerts over another.

This effect on connectivity also led to improvement in actual cognitive performance: Subjects tested significantly better for working memory tasks after the admission of green tea extract.

For the study healthy male volunteers received a soft drink containing several grams of green tea extract before they solved working memory tasks. The scientists then analyzed how this affected the brain activity of the men using magnetic resonance imaging (MRI).

The MRI showed increased connectivity between the parietal and the frontal cortex of the brain. These neuronal findings correlated positively with improvement in task performance of the participants. "Our findings suggest that green tea might increase the short-term synaptic plasticity of the brain," says Borgwardt.

The study has been published in the journal Psychopharmacology.