Dietary
cocoa flavanols reverse age-related memory decline in mice
Dietary cocoa flavanols -- naturally occurring bioactives
found in cocoa -- reversed age-related memory decline in healthy older adults,
according to a study led by Columbia University Medical Center (CUMC)
scientists.
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.
Previous work, including by the laboratory of senior
author Scott A. Small, MD, had 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, Dr. Small and his colleagues 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.
Dr. Small is the Boris and Rose Katz Professor of
Neurology (in the Taub Institute for Research on Alzheimer's Disease and the
Aging Brain, the Sergievsky Center, and the Departments of Radiology and
Psychiatry) and director of the Alzheimer's Disease Research Center in the Taub
Institute at CUMC.
A cocoa flavanol-containing test drink prepared
specifically for research purposes was produced by the food company Mars,
Incorporated, which also partly supported the research, 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.
In the CUMC study, 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.
"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, PhD, associate professor of neuropsychology at the Taub Institute.
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.
He cautioned, however, that the findings need to be replicated in a larger
study -- which he and his 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 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.
Two innovations by the investigators made the study
possible. One was a new information-processing tool that allows the imaging
data to be presented in a single, three-dimensional snapshot, rather than in
numerous individual slices.
The tool was developed in Dr. Small's lab by Usman
A. Khan, an MD-PhD student in the lab, and Frank A. Provenzano, a biomedical
engineering graduate student at Columbia.
The other innovation was a
modification to a classic neuropsychological test, allowing the researchers to
evaluate memory function specifically localized to the dentate gyrus. The
revised test was developed by Drs. Brickman and Small.
Besides flavanols, exercise has been shown in previous
studies, including those of Dr. Small, to 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 saythat exercise is not
beneficial for cognition. It may be that older people need more intense
exercise to reach VO2max levels that have therapeutic effects."
The article is titled, "Enhancing dentate gyrus
function with dietary flavanols improves cognition in older adults," The
other contributors are: Lok-Kin Yeung (CUMC), Wendy Suzuki (New York
University, New York, NYU), Hagen Schroeter (Mars, Incorporated, McLean VA),
Melanie Wall (CUMC and New York State Psychiatric Institute, New York NY), and
Richard Sloan (CUMC and New York State Psychiatric Institute).
The study was
supported by grants from the National Institutes of Health (AG034618 and
AG035015), the James S. McDonnell Foundation, the McKnight Brain Research
Foundation, and Mars, Incorporated (Editor's note - Mars is a candy maker - Snickers, Three Musketeers, etc.).
Hagen Schroeter is employed by Mars, Incorporated, a
company with long-term research and commercial interests in cocoa flavanols and
procyanidins. The other authors declare no financial or other conflicts of
interest.
Story Source:
The above story is based on materials provided by Columbia
University Medical Center. Note: Materials may be edited for
content and length.
Journal Reference:
Adam M Brickman, Usman A Khan, Frank A Provenzano,
Lok-Kin Yeung, Wendy Suzuki, Hagen Schroeter, Melanie Wall, Richard P Sloan,
Scott A Small.Enhancing dentate gyrus function with dietary flavanols
improves cognition in older adults. Nature
Neuroscience, 2014; DOI: 10.1038/nn.3850
Cite This Page:
Columbia University Medical Center. "Dietary cocoa
flavanols reverse age-related memory decline in mice." Science Daily,
26 October 2014.
<www.sciencedaily.com/releases/2014/10/141026195046.htm>.
