Green tea has been hailed for many health benefits, including its effects against cancer, heart disease and type 2 diabetes. Now, new research suggests the beverage can enhance our brain's cognitive functions, particularly the working memory.
The research team - including Prof. Christoph Beglinger and Prof. Stefan Borgwardt of the University Hospital of Basel in Switzerland - says their findings suggest that green tea could be promising in the treatment of cognitive impairments associated with neuropsychiatric disorders, such as dementia.
They recently published their findings in the journal Psychopharmacology.
Green tea, native to China and India, is produced from the leaves of the Camellia sinensis bush. Unlike other teas, green tea is made from unoxidized leaves. This minimal processing means it is rich in antioxidants.
Past research has associated the beverage with many health benefits. Last year, for example, Medical News Today reported on a study suggesting that green tea may reduce stroke risk, while another study found that it could help fight prostate cancer.
Previous studies have also suggested that green tea may have a beneficial impact on the brain's cognitive functions. However, according to the researchers of this most recent study, the exact mechanisms behind this claim have been unclear.
Green tea 'boosts connectivity between parietal and frontal cortex of the brain'
To further investigate, the team conducted a study using 12 healthy male volunteers with a mean age of 24.1 years.
Participants were given a milk whey-based soft drink containing 27.5 g of green tea extract, while others were given a soft drink without the green tea extract. Volunteers were unaware of which drink they had been given.
The participants were then required to carry out a series of working memory tasks. During these tasks, their brain activity was measured using magnetic resonance imaging (MRI).
The researchers found that the participants who consumed the soft drink with the green tea extract showed increased connectivity between the right superior parietal lobule and the frontal cortex of the brain. This activity correlated with improved performance on the working memory tasks.
Commenting on the findings, the researchers say:
"The present study shows that green tea extract enhances functional connectivity from the parietal to the frontal cortex during working memory processing in healthy controls.
Interestingly, this effect on effective connectivity was related to the green tea induced improvement in cognitive performance. Our findings provide first insights into the neural effect of green tea on working memory processing at the neural network level, suggesting a mechanism on short-term plasticity of interregional brain connections."
Green tea may help in treatment of dementia
According to the research team, since green tea appears to increase connectivity between frontal and parietal brain regions during working memory processing, it is worth testing the efficacy of green tea for the treatment of disorders involving cognitive impairments, such as dementia.
But they note there are some limitations in their study that need to be considered. They point out that, in contrast to the imaging results, there was no significant effect found between green tea consumption and task performance.
"However, we found a strong trend toward improved performance," they add, "suggesting that our study sample was too small to achieve differences on behavioral parameters."
In addition, the researchers note that the participants drank a soft drink containing green tea extract, not a pure green tea extract. They point out that if the participants drank a pure green tea extract, this would have avoided effects of other components, such as caffeine, which may have had some impact on participants' cognitive performance.
Our article on the health benefits of green tea reveals some other ways in which the beverage may be good for you, as well as potential risks from drinking green tea.