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Cocoa's Antioxidants Reversed Seniors' Memory Decline
Trial offers first evidence that age-related memory loss can be curbed by cocoa, and shows how it works

11/03/2014 By Craig Weatherby
Brain-health news from Columbia University is very big indeed, and comes in two exciting parts.
 
First, Columbia scientists have confirmed that – as suspected – a tiny brain region plays a key role in age-related declines in thinking and memory.
 
And they proved this by testing the effects on that region and on people's cognitive (thinking and memory) capacities, after the subjects had consumed rare, potent antioxidants from cocoa.
 
Before we examine the study, it's important to distinguish between “normal”, age-related cognitive decline (ARCD) and Alzheimer's disease.
 
Age-related cognitive decline (ARCD): The basics
As people age, they typically suffer some decline in cognitive abilities including learning, and remembering things like the names of new acquaintances.
 
This decline is not inevitable, and is affected by genes, exercise, and mental activity. And a recent clinical study suggests that it may be possible to delay or prevent ARCD with a healthy diet and lifestyle … see “Can Dementia be Defeated Naturally?”.
 
This normal age-related cognitive decline (ARCD) starts in early adulthood but usually has no noticeable impact until people reach their fifties or sixties.
 
ARCD is different from Alzheimer's, because that devastating disease actually damages and destroys neurons in patients' brain, including their memory circuits.
 
Prior research showed that changes in a specific part of the brain – called the “dentate gyrus” – are associated with age-related memory decline.
 
But until now, the evidence from human studies showed only a correlation between changes in the dentate gyrus and ARCD, and could not prove that those changes cause the condition.
 
To see if changes in the dentate gyrus cause ARCD in people, Dr. Small and his colleagues tested whether “antioxidant” compounds in cocoa called flavanols could improve the function of this brain region … and also improve memory.
 
(The term “antioxidant” is commonly applied to flavanols and other beneficial natural chemicals, but is misleading … see our sidebar, “The facts about antioxidants in foods”.)
 
The facts about “antioxidants” in foods
The polyphenol and carotenoid compounds in whole plant foods are commonly called “antioxidants” because they behave that way in test tube experiments.
 
But in general, these health allies do not exert direct antioxidant effects in the body… at least not to a very substantial extent.
 
Instead, polyphenols appear to exert strong indirect effects on oxidation and inflammation via so-called “nutrigenomic” effects on gene switches (e.g., transcription factors) in our cells.
 
Polyphenols' nutrigenomic effects tend to moderate inflammation and stimulate the body's own antioxidant network … which includes enzymes, lipoic acid, CoQ10, melatonin, and vitamins C and E.
 
The richest known food source of polyphenols are raw (non-alkalized / non-“Dutched”) cocoa, berries, curcumin (turmeric root), plums, prunes, tea, coffee, extra virgin olive oil, beans, and whole grains.
 
(Highly beneficial procyanidin-type polyphenols abound in cocoa, dark-hued berries – e.g., blackberries, blueberries açaí berries – grapes, red wine, and tea. Comparably beneficial anthocyanin-type polyphenols abound in cherries and most berries.)
 
Extra virgin olive oil is uniquely rich in hydroxytyrosol, oleuropein, oleocanthal, and other tyrosol esters … a particularly potent class of polyphenols with clinically documented vascular and brain benefits.
They knew that flavanols extracted from cocoa beans were previously found to improve neuronal (brain cell) connections in the dentate gyrus region in mice.
 
The Columbia team also knew that – as we reported in 2007 – “Aging Brains Appear to Benefit from Foodborne Antioxidants” and that cocoa has shown promise in several human studies … see “Extra-Dark Chocolate Eased Memory Tasks”, “Cocoa May Boost Eyes and Brain”, and “Cocoa Bolstered Seniors' Brains”.
 
Columbia University study shows that cocoa can reverse normal memory loss
The Columbia team tested the effects of a test drink made by chocolate maker Mars, Inc., which also partly supported the research (Brickman AM et al. 2014).
 
Mars scientists use a proprietary process to extract the flavanol-type antioxidants from cocoa beans.
 
Most cocoa is treated with alkali ... a standard process called Dutching, which destroys almost all of cocoa's beneficial antioxidants, including its flavanols.
 
(Our extra-dark chocolate contains 80% cocoa solids, which have not been treated with alkali. Brunswick Laboratories found it contains antioxidants at levels that rival those in natural, non-Dutched cocoa powder.)
 
Flavanols abound only in green tea and non-Dutched cocoa, which feature flavanols called catechins. Much smaller amounts occur in grapes, apples, and certain fruits and vegetables.
 
Scientists from Columbia University Medical Center (CUMC) recruited 37 healthy volunteers aged 50 to 69, and randomly assigned them to one of two groups for their three-month study:
  • High-flavanol diet (900 mg of flavanols a day)
  • Low-flavanol diet (10 mg of flavanols a day).
Each participant underwent brain imaging and memory tests before and after the study.
 
The brain imaging measured blood volume in the dentate gyrus – a measure of metabolic rate.
 
Meanwhile, the memory test (a 20-minute pattern-recognition exercise) was designed to evaluate a type of memory controlled by the dentate gyrus.
 
“When we imaged our research subjects' brains, we found noticeable improvements in the function of the dentate gyrus in those who consumed the high-cocoa-flavanol drink,” said lead author Adam M. Brickman, Ph.D. (CUMC 2014).
 
The high-flavanol group also performed significantly better on the memory test.
 
If a participant had the memory of a typical 60-year-old at the beginning of the study, after three months that person on average had the memory of a typical 30- or 40-year-old,” said Dr. Small (CUMC 2014).
 
He cautioned, however, that the findings need to be replicated in a larger study—which he and his team plan to do.
 
The same drink used in the CUMC study has also been shown to improve cardiovascular health.
 
Brigham and Women's Hospital in Boston recently announced an NIH-funded study of 18,000 men and women to see whether flavanols can help prevent heart attacks and strokes.
 
The researchers point out that the product used in the study is not the same as chocolate, and they caution against an increase in chocolate consumption in an attempt to gain this effect.
 
However, other studies have found significant benefits from consuming normal amounts of non-Dutched cocoa and very dark chocolate (e.g., bars with 80% or more cocoa solids).
 
And previous studies by the CUMC team showed that exercise can improve memory and dentate gyrus function in younger people.
 
In the current study, the researchers were unable to assess whether exercise had an effect on memory or on dentate gyrus activity.
 
“Since we didn't reach the intended VO2max (maximal oxygen uptake) target,” said Dr. Small, “we couldn't evaluate whether exercise was beneficial in this context. This is not to say that exercise is not beneficial for cognition. It may be that older people need more intense exercise to reach VO2max levels that have therapeutic effects.” (CUMC 2014)
 
Stay tuned … we'll continue to follow researchers examining whether and how cocoa and dark chocolate can benefit human health.
 
 
Sources
  • Brickman AM, Khan UA, Provenzano FA, Yeung LK, Suzuki W, Schroeter H, Wall M, Sloan RP, Small SA. Enhancing dentate gyrus function with dietary flavanols improves cognition in older adults. Nat Neurosci. 2014 Oct 26. doi: 10.1038/nn.3850. [Epub ahead of print]
  • Columbia University Medical Center (CUMC). Dietary Flavanols Reverse Age-Related Memory Decline: Findings strengthen link between specific brain region and normal memory decline. October 26, 2014. Accessed at http://newsroom.cumc.columbia.edu/blog/2014/10/26/flavanols-memory-decline/  
  • Desideri G, Kwik-Uribe C, Grassi D, Necozione S, Ghiadoni L, Mastroiacovo D, Raffaele A, Ferri L, Bocale R, Lechiara MC, Marini C, Ferri C. Benefits in cognitive function, blood pressure, and insulin resistance through cocoa flavanol consumption in elderly subjects with mild cognitive impairment: the Cocoa, Cognition, and Aging (CoCoA) study. Hypertension. 2012 Sep;60(3):794-801. doi: 10.1161/HYPERTENSIONAHA.112.193060. Epub 2012 Aug 14.
  • Francis ST, Head K, Morris PG, Macdonald IA. The effect of flavanol-rich cocoa on the fMRI response to a cognitive task in healthy young people. J Cardiovasc Pharmacol. 2006;47 Suppl 2:S215-20.
  • Sies H, Hollman PC, Grune T, Stahl W, Biesalski HK, Williamson G. Protection by flavanol-rich foods against vascular dysfunction and oxidative damage: 27th Hohenheim Consensus Conference. Adv Nutr. 2012 Mar 1;3(2):217-21. doi: 10.3945/an.111.001578.
  • Sokolov AN, Pavlova MA, Klosterhalfen S, Enck P. Chocolate and the brain: neurobiological impact of cocoa flavanols on cognition and behavior. Neurosci Biobehav Rev. 2013 Dec;37(10 Pt 2):2445-53. doi: 10.1016/j.neubiorev.2013.06.013. Epub 2013 Jun 26. Review.