Researchers say that naturally occurring flavanols in cocoa reversed age-related memory decline in older adults.
According to the research team, including senior author Dr. Scott Small, memory decline starts in early adulthood, although it does not become highly noticeable until we reach our 50s or 60s - when it becomes known as age-related memory decline.
Past studies have suggested that this form of memory decline may stem from changes in the function of a brain region known as the dentate gyrus, but proving the association to be causal has been a challenge for researchers.
Flavanols found in cocoa beans have been linked to improvements in brain connections in the dentate gyrus of mice. As such, Dr. Small and colleagues wanted to see whether these flavanols would boost the function of the dentate gyrus in humans and improve memory.
High- versus low-flavanol diet
To reach their findings, the researchers enrolled 37 healthy individuals aged 50-69 to their study.
For 3 months, some of the participants were randomized to follow a high-flavanol diet, containing 900 mg of flavanols each day. Other participants followed a low-flavanol diet, containing only 10 mg of flavanols a day.
Flavanols were consumed via a cocoa drink produced by food company Mars. The drink - made specifically for research purposes - was produced to contain flavanols that are usually found in raw cocoa, many of which are lost when cocoa is processed. Mars also partly funded the study.
At study baseline and when the study ceased, each participant underwent brain imaging using a novel technique developed in Dr. Small's laboratory. This allowed the researchers to assess the blood volume specific to the dentate gyrus, which they say is a measure of metabolism in this region.
The subjects were also required to participate in memory tests at both time points, which involved completing a 20-minute pattern-recognition task. The task - also developed by Dr. Small and colleagues - allowed them to assess a form of memory that the dentate gyrus controls.
High-flavanol diet linked to better dentate gyrus function, memory
The team found that the participants who followed the high-flavanol diet demonstrated improved function in the dentate gyrus, compared with those who followed the low-flavanol diet. Furthermore, participants in the high-flavanol group performed much better on memory tests.
Dr. Small comments:
"If a participant had the memory of a typical 60-year-old at the beginning of the study, after 3 months that person on average had the memory of a typical 30- or 40-year-old."
The team stresses that the cocoa drink used in this study is not the same as chocolate. Because chocolate has been processed, it does not contain flavanols at high levels like the raw cocoa used to make the drink in this research. Therefore, the team warns against increasing chocolate consumption to improve memory.
Although their results appear to suggest a causal link between dentate gyrus function in humans and age-related memory, the researchers say the findings need to be replicated in a larger study - something they plan to conduct in the future.
It is not only cocoa flavanols that have been linked to improved memory. Earlier this year, another study published in Nature Neuroscience claimed a dose of caffeine after a learning session could boost long-term memory. Most recently, MNT reported on a study linking light alcohol consumption to improved memory in adults over the age of 60.