Green tea promotes increased activity in brain’s working memory center

Neural effects of green tea extract on dorsolateral prefrontal cortex
– Source: European Journal of Clinical Nutrition, Aug 29, 2012

By Stefan J Borgwardt, MD, et al.

[Note: According to Wikipedia, “Working memory is the system that holds multiple pieces of transitory information in the mind when needed for verbal and nonverbal tasks such as reasoning and comprehension, and to make them available for further information processing. It is not the same as short term memory [holds passing information, such as a phone number noted, for a very brief time]. Working memory tasks are tasks which require monitoring or manipulation of information or behaviors as part of directed action to a goal.” The brain’s dorsolateral prefrontal cortex, where these researchers saw dose-related increases in activity among subjects ingesting green tea extract vs controls, is considered important in working memory processing, and regulation of task-oriented thinking and action.]

Background/Objectives: Green tea is being recognized as a beverage with potential benefits for human health and cognitive functions.

In vivo studies provide preliminary evidence that green tea intake may have a positive role in improving effects on cognitive functions.

We aimed to examine the neural effects of green tea extract on brain activation in humans.

Subjects/Methods: Functional magnetic resonance imaging was recorded while 12 healthy volunteers performed a working memory task following administration of 250 or 500 ml of a milk whey based green tea containing soft drink or milk whey based soft drink without green tea as control in a double-blind, controlled repeated measures within-subject design with counterbalanced order of substance administration.

A whole-brain analysis with a cluster-level threshold of P<0.001 (unadjusted) was followed by an a priori-defined region of interest (ROI) analysis of the dorsolateral prefrontal cortex (DLPFC) including a cluster-level threshold of P<0.05 and family-wise error (FWE) adjustment for multiple comparisons. Results:

• Whole-brain analyses revealed no significant effects after correction for multiple comparisons (FWE P<0.05). • Using a region of interest (ROI) approach, green tea extract increased activation in the DLPFC relative to a control condition (FWE P<0.001). • This neural effect was related to green tea dosage. • Green tea extract was not associated with any significant attenuation [reduced intensity] in regional activation relative to control condition. Conclusions:

• These data suggest that green tea extract may modulate brain activity in the DLPFC, a key area that mediates working memory processing in the human brain.

• Moreover, this is the first neuroimaging study implicating that functional neuroimaging methods provide a means of examining how green tea extract acts on the brain.

Source: European Journal of Clinical Nutrition, Aug 29, 2012. PMID: 22929964, by Borgwardt S, Hammann F, Scheffler K, Kreuter M, Drewe J, Beglinger C. University Hospital Basel, Medical Image Analysis Centre and Department of Psychiatry, University of Basel, Basel, Switzerland; Institute of Psychiatry, King’s College London, UK.

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