A humble cup of tea a day can keep dementia away, and this is specially so for those who are genetically at risk of developing the debilitating disease, according to a recent study led by Assistant Professor Feng Lei from the Department of Psychological Medicine at National University of Singapore's (NUS) Yong Loo Lin School of Medicine.
The longitudinal study involving 957 Chinese seniors aged 55 years or older has discovered that daily consumption of tea decreases the risk of cognitive decline in the elderly by 50%, whereas APOE e4 gene carriers who are genetically predisposed to Alzheimer's disease may experience a reduction in cognitive impairment risk by as much as 86%.
The research team also discovered that the neuroprotective role of tea consumption on cognitive function is not confined to a particular type of tea - so long as the tea is brewed from tea leaves, such as green, black or oolong tea.
"While the study was conducted on Chinese elderly, the results could apply to other races as well. Our findings have important implications for dementia prevention. Despite high quality drug trials, effective pharmacological therapy for neurocognitive disorders such as dementia still remains elusive and current prevention strategies are far from satisfactory. Tea is one of the most widely consumed beverages in the world. The data from our study suggests that a simple and inexpensive lifestyle measure such as daily tea drinking can reduce a person's risk of developing neurocognitive disorders in late life," explained Asst Prof Feng.
He added, "Based on current knowledge, this long term benefit of tea consumption is due to the bioactive compounds in tea leaves, such as catechins, theaflavins, thearubigins and L-theanine. These compounds exhibit anti-inflammatory and antioxidant potential and other bioactive properties that may protect the brain from vascular damage and neurodegeneration. Our understanding of the detailed biological mechanisms is still very limited, so we do need more research to find out definitive answers."
In this study, tea consumption data were collected from the participants, who are community-living elderly, from 2003 to 2005. At regular intervals of two years, these seniors were assessed on their cognitive function using standardised tools until 2010. Information on lifestyles, medical conditions, physical and social activities was also collected. Those potential confounding factors were carefully controlled in statistical models to ensure the robustness and the validity of the findings.
Asst Prof Feng and his team are planning to engage in further studies to better understand the impact of Asian diet on cognitive health in aging. They are also keen to investigate the effects of the bioactive compounds in tea and test them more rigorously through the assessment of their biological markers and by conducting randomised controlled trials or studies that assign participants into experimental groups or control groups randomly to eliminate biased results.
According to United Nations, in 2017, there were an estimated 962 million people aged 60 or over in the world, comprising 13 per cent of the global population. Also, the population aged 60 or above is growing at a rate of about 3 per cent per year. The number of older persons in the world is projected to be 1.4 billion in 2030 and 2.1 billion in 2050, and could rise to 3.1 billion in 2100. Since the global population is rapidly ageing, and since that does amplify the incidence of dementia, tea can do a lot to lower the risk of dementia in the elderly.