Characterized by symptoms including memory loss and hindered judgment, dementia is a common condition that can affect daily functioning for years or the remainder of a lifetime.
From 2006 to 2010, a team made up of neurology researchers from Fudan University-affiliated Huashan Hospital and the Department of Neurology of Qingdao University-affiliated Qingdao Municipal Hospital conducted followed a large cohort of people in the United Kingdom. The study found that, compared with non-tea drinkers, people who favored tea drinks achieved a 16 percent lower overall risk of dementia.
During the four years, the team selected 377,592 volunteers from 22 regions in the UK with an average age of 58.49, of which 54.3 percent were women.
Researchers divided study participants into six groups: no tea drinking at all; one to two cups per day; three to four cups; five to six cups; seven to eight cups; and nine or more cups per day respectively.
Proportional hazard regression models show a significant association between tea consumption and reduced risk of dementia. Specifically, those drinking one to two cups daily had their risk of dementia reduced by 17.7 percent; three to four cups by 20.8 percent; and five to six cups by 19.7 percent. However, when consumption exceeded six cups per day, the risk of dementia was no different than that of non-tea drinkers.
Further analysis into dementia types showed that compared with participants who didn't drink tea at all, those who drank one to four cups per day had a 16.3 to 19.1 percent lower risk of developing Alzheimer's disease, but there was no significant difference after more than five cups per day. In vascular dementia, taking one to six cups per day can reduce the incidence rate by 25 to 29.2 percent.
The research team then followed the study participants for more than nine years and recorded a total of 5,122 cases of dementia.
According to the research team, tea consumption has been linked to protection against several diseases. Tea leaves contain various biomacromolecules, the most notable among them being polyphenols in green tea, which can evoke a wide range of cellular antioxidant and nerve rescue activities with the effect of preventing memory deficits. Biomacromolecules also have anti-inflammatory effects, which can prevent cognitive decline.