How Green Tea Protects Against Alzheimer’s DiseaseAugust 2014
By Michael Downey
Live Images Reveal Immediate Memory Enhancement
Data about the consumption of black, oolong, or green tea and cognitive function was obtained and examined for over 1,000 Japanese subjects age 70 or over during a period of four months. Analysis of the data revealed that consumption of 2 or more cups per day of green tea reduced the odds of cognitive impairment by 54%, whereas those that consumed equal amounts of black or oolong tea had an odds reduction of only 13%.20
However, this was a cross-sectional study that did not provide hard scientific evidence of effectiveness. To achieve more definitive results, scientists use double-blind, placebo-controlled studies. Unfortunately, it is extremely difficult to conduct intervention studies that would continually monitor human volunteers for adherence and allow for the time required to sufficiently establish, through memory tests, whether green tea enhances memory and recall.
But in a recent study published in the European Journal of Clinical Nutrition, scientists performed the first neuroimaging study allowing them to see the real-time effects of green tea extract inside the human brain’s working-memory area!19
On four separate occasions, with a one-week interval between sessions, healthy volunteers between 21 and 28 years old consumed either a placebo drink, a 250 mL, or a 500 mL combination drink containing green tea extract. The researchers used a feeding tube to rule out taste as a factor.
After consuming the drink, the subjects then performed a memory-stimulating task while researchers simultaneously monitored their brain function using functional magnetic resonance imaging, or fMRI, to zero-in on the working-memory region.
Thanks to this imaging technique, rather than relying on possibly imperceptible differences in performance on a brief memory test following a single dose or even a week of supplementation—scientists could watch the volunteers’ working memories in action on a second-by-second basis.
Compared to placebo, the beverages containing green tea extract significantly boosted activity in the dorsolateral prefrontal cortex—the area of the brain used for working-memory processing.19,59 This small region allows the brain to simultaneously store and process information, and it facilitates complex cognitive tasks, such as language comprehension, reasoning, and learning.
Activity in this memory area was increased even further by the higher dose drink.19 This dose-related response backs up the cause-and-effect connection between green tea and improved memory processing.
Not only did this finding confirm green tea extract’s immediate and significant enhancement of working-memory activity, the researchers noted that it also established for the first time the effectiveness of neuroimaging in observing green tea’s instant impact on the human brain.19
Taken together, all of these findings indicate green tea extract’s marked protection of brain neurons by inhibiting the formation of amyloid-beta fibrils and other processes associated with Alzheimer’s disease and, possibly, by triggering the production of new brain neurons.
Amyloid-beta plaques slowly form in the brain and interfere with nerve cells, often killing them. The tragic result too often is Alzheimer’s disease—the sixth leading cause of American deaths.
Accumulating evidence demonstrates that green tea extract may reduce the risk of Alzheimer’s disease and other forms of cognitive decline by 54%.
Studies show that the powerful green tea compound EGCG prevents formation of amyloid plaques, breaks down existing amyloid plaques,and promotes production of new neurons in the adult hippocampus.
In an exciting development, scientists used MRI scanning for the first time in a human clinical setting to watch the immediate boost in working-memory activity that green tea extract produces—illustrating in real-time the potent neuroprotection of green tea compounds.
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