Tea drinking slashes the risk of cognitive decline and Alzheimer's disease: Singapore population-based analysis

Put the kettle on: Frequent tea consumption reduces the risk of cognitive decline. ©iStock

Tea consumption halves the risk of cognitive impairment for people 55 years old and above, and also dramatically reduces the risk of developing Alzheimer's disease among those at greater genetic risk.

These were the key findings of a longitudinal study involving 957 seniors 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.

It found that regular consumption of tea lowers the risk of cognitive decline in the elderly by 50%, while APOE e4 gene carriers who are genetically at risk of developing 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 limited 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 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,” said assistant professor Feng.

However, he said much more work is needed to fully understand the biological mechanisms responsible for these benefits.

Assistant professor Feng 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."

Robust findings

In this study, tea consumption information was collected from the participants, who were 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 were also collected. Those potential confounding factors were controlled in statistical models to ensure the robustness of the findings.

The paper, published in The Journal of Nutrition, Health & Aging, stated: "A total of 72 incidents of neurocognitive disorders (NCD) were identified from the cohort. Tea intake was associated with lower risk of incident NCD, independent of other risk factors. Reduced NCD risk was observed for both green tea (OR=0.43) and black/oolong tea (OR=0.53) and appeared to be influenced by the changing of tea consumption habit at follow-up. Using consistent non-tea consumers as the reference, only consistent tea consumers had reduced risk of NCD (OR=0.39). Stratified analyses indicated that tea consumption was associated with reduced risk of NCD among females (OR=0.32) and APOE e4 carriers (OR=0.14) but not males and non APOE e4 carriers."

It concluded that regular tea consumption was associated with lower risk of neurocognitive disorders among Chinese elderly. Gender and genetic factors could possibly modulate this association, it added.

 

Source: The Journal of Nutrition, Health & Aging

DOI: 10.1007/s12603-016-0687-0

"Tea consumption reduces the incidence of neurocognitive disorders: Findings from the Singapore longitudinal aging study."

Authors: L Feng, et al.

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