Your Brain on Tea

From ancient China to your kitchen, tea has shaped our culture and our brains. Lillian Loescher describes what this could indicate.

From ancient China to your kitchen, tea has shaped our culture and our brains. Lillian Loescher describes what this could indicate.

That cuppa you have in the morning may be more beneficial to your health than you think. A study recently published in the scientific journal, Aging, describes the positive effects of regular tea consumption on brain structure and touted its protective impacts on age-related decline in brain organization. This comes as no surprise as there have been decades of scientific research about the positive effects of tea consumption on the brain.

Scientist Junhua Li and colleagues showed the first evidence of the “positive contribution of tea drinking to brain structure and [their research] suggests a protective effect on age-related decline in brain organization”. Junhua Li and colleagues found that those who habitually drank tea had better functional connectivity within the default mode network (DMN) in their brains as compared to those who did not drink tea habitually. The DMN is an interconnected set of structures in the brain between the dorsal medial system and the medial temporal system. These structures are responsible for attention, memory, awareness and spatial navigation as well as higher level thought processes including predicting the future actions of people around you and an ability to reflect on others thought processes and beliefs.

The ability to reflect on others thought processes and beliefs is what psychologists call having a theory of mind. It has been well documented that people on the autism spectrum as well as those with Alzheimer’s disease have an impaired theory of mind. One large medical review looking at the effect of tea on the prevention of Alzheimer’s disease found that 8 out of 9 studies concluded that herbal tea had a neuroprotective role and contributed to the prevention of Alzheimer’s disease. Thus, showing further evidence supporting the positive role of habitual tea consumption on the DMN.

The article produced by Junhua and colleagues has also shown that between the group of older adults who drink tea regularly and the group of older adults who do not drink tea regularly there was “higher structural network efficiency found in older adults who had habitual tea drinking. Relative to the non-tea drinking group, the tea drinking group had less topological distance between brain regions and more efficient interregional connectivity.

One of the hallmarks of an aging brain is leftward asymmetry in structural connectivity within the hemispheres of the brain, this can be observed using magnetic resonance imaging (MRI). Scientists have shown that “the suppression of hemispheric asymmetry in structural connectivity was associated with tea drinking, tending to be more symmetric in structural connectivity. Specifically, the non-tea drinking group exhibited significantly leftward asymmetry…This hemispheric asymmetry in structural connectivity has been associated with brain ageing”.

A separate study looking at the effects of tea on the brain in both humans and animals found that an antioxidant in tea (called catechin) to be extremely beneficial for cognition. As compared to placebo groups, enhancements in memory recognition and working memory were observed following tea consumption over extended periods of time.

Since tea consumption has been shown to be beneficial to brain function, connectivity and symmetry throughout lifetime one must wonder how tea came to be.

The first known monograph of tea was written by LuYu between 760CE and 762CE and is titled: The Classic of Tea. The book describes how to create the perfect cup of tea as well as the therapeutic benefits that tea has. It is said that tea originated in the Yuunan region of China around 4,000 years ago as a medical drink that was believed to represent the harmony and mysterious unity of the universe. Legend has it that tea was discovered by accident by an emperor of China around 2737BC when he was drinking a bowl of boiled water. A breeze hit and some leaves landed in his bowl. Noting the colour change and good taste the emperor was surprised and thus tea became part of the culture. Thousands of years would pass before tea would make its way over to Ireland and the UK.

The first advertisement for tea in the UK appeared in 1658 and officially the tea trade began in 1664. The exact date when tea consumption became popular in Ireland is not known, but “the existence of silver teapots from the 1720s suggests that it was well-established by then”. For thousands of years across the world tea has been consumed for medicinal and social purposes. The scientific interest in the health benefits of tea will continue to percolate our cultural milieu and perhaps the nature of preventative medicine will be partly shaped by tea consumption.