Cocoa Compound Reverse Age-Related Memory Decline

Dietary cocoa flavanols reversed age-related memory decline
 in healthy older adults. (Credit: Mars, Incorporated)
Dietary cocoa flavanols, naturally occurring bioactives found in cocoa, reversed age-related memory decline in healthy older adults. The study, published in the online issue of Nature Neuroscience, provides the first direct evidence that one component of age-related memory decline in humans is caused by changes in a specific region of the brain and that this form of memory decline can be improved by a dietary intervention.

As people age, they typically show some decline in cognitive abilities, including learning and remembering such things as the names of new acquaintances or where one parked the car or placed one's keys. This normal age-related memory decline starts in early adulthood but usually does not have any noticeable impact on quality of life until people reach their fifties or sixties. Age-related memory decline is different from the often-devastating memory impairment that occurs with Alzheimer's, in which a disease process damages and destroys neurons in various parts of the brain, including the memory circuits.

Previous work, have shown that changes in a specific part of the brain, the dentate gyrus, are associated with age-related memory decline. Until now, however, the evidence in humans showed only a correlational link, not a causal one. To see if the dentate gyrus is the source of age-related memory decline in humans, the researchers tested whether compounds called cocoa flavanols can improve the function of this brain region and improve memory. Flavanols extracted from cocoa beans had previously been found to improve neuronal connections in the dentate gyrus of mice.

A cocoa flavanol-containing test drink was prepared specifically for research purposes using a proprietary process to extract flavanols from cocoa beans. Most methods of processing cocoa remove many of the flavanols found in the raw plant. 37 healthy volunteers, ages 50 to 69, were randomized to receive either a high-flavanol diet (900 mg of flavanols a day) or a low-flavanol diet (10 mg of flavanols a day) for three months. Brain imaging and memory tests were administered to each participant before and after the study. The brain imaging measured blood volume in the dentate gyrus, a measure of metabolism, and the memory test involved a 20-minute pattern-recognition exercise designed to evaluate a type of memory controlled by the dentate gyrus.

The brain area outlined in yellow is the hippocampus; the
 dentate gyrus is shown in green and the entorhinal cortex in
 purple. The dentate gyrus is distinct from the entorhinal cortex,
 the hippocampal region affected in early-stage Alzheimer's
 disease. (Credit: Lab of Scott A. Small, M.D.)
Noticeable improvements were found in the function of the dentate gyrus in those who consumed the high-cocoa-flavanol drink. 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. The researchers cautioned, however, that the findings need to be replicated in a larger study, which the team plan to do.

Flavanols are also found naturally in tea leaves and in certain fruits and vegetables, but the overall amounts, as well as the specific forms and mixtures, vary widely.

The precise formulation used in the study has also been shown to improve cardiovascular health. A study of 18,000 men and women was launched 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.