Tea for Alzheimer Prevention.

The availability of empirical data from human studies in recent years have lend credence to the old axiomatic wisdom that health benefits of tea drinking extend to the area of cognition. Specifically, there is increasing interest as to whether tea drinking can delay or even prevent the onset of Alzheimer's disease (AD). Data from several cross-sectional studies have consistently shown that tea drinking is associated with better performance on cognitive tests. This association is supported by longitudinal data from the Singapore Longitudinal Aging Study, the Chinese Longitudinal Healthy Longevity Survey and the Cardiovascular Health Study. The only two published longitudinal analyses on clinical outcome reported conflicting results: one study reported that mid-life tea drinking was not associated with risk reduction of Alzheimer's disease in late life while the other one found that green tea consumption reduced the incidence of dementia or mild cognitive impairment. Two small trials from Korea and Japan reported encouraging but preliminary results. While the existing evidence precludes a definite conclusion as to whether tea drinking can be an effective and simple lifestyle preventive measure for AD, further research involving longer-term longitudinal studies and randomized controlled trials is clearly warranted to shed light on this topic of immense public health interest. Biological markers of tea consumption and Alzheimer diseases should be employed in future research to better delineate the underlying mechanisms of tea drinking's protective effect on cognition.