Flavanols in cocoa may improve brain function in older adults

1. Older adults who randomized to a high cocoa–containing diet had improved scores on a task designed to test their cognitive function at 3 months compared to subjects given low cocoa–containing diet.

2. This improvement in cognitive ability was associated with enhanced dentate gyrus (DG) function in the brain.

Evidence Rating Level: 2 (Good)

Study Rundown: Age-related cognitive decline is considered normal, though affects some aging adults more severely than others. Part of this heterogeneity is thought to result from lifestyle variability. Modifications in aerobic exercise have been shown to improve cognitive function, highlighting the potential for non-pharmacologic therapies to mitigate cognitive decline. Specific cognitive declines are often associated with increased dysfunction in specific regions of the brain. Studies suggest the DG, a region of the hippocampus involved in learning and memory, becomes less functional with age, and specifically enhancing DG function (through genetic modifications or dietary modification with flavanol) may lead to increased cognitive ability in mice.

In this study, researchers paired a novel image-recognition test with high-resolution brain scans to correlate changes in cognitive ability and region-specific brain function. Elderly (50-69 years of age) human participants were assigned to one of four groups for three months (exercise or no exercise paired with a low or high dose of dietary cocoa supplement). Participants were evaluated before and after the trial. Impressively, subjects given high cocoa diet performed significantly better on the cognitive test relative to subjects given the low cocoa diet. The DG of the brain showed increased functionality in the high-dose cocoa supplement groups, thus correlating the region-specific brain decline with specific forms of cognitive decline. This preliminary study suffered from having few subjects in each treatment group (< 10 patients/group, majority women), and did not extend their studies to 70+-year-old adults to examine DG improvement in more advanced cases of decline. Authors declared competing financial interests. Ultimately, these exciting findings suggest incorporating cocoa into the diet may help improve cognition in older adults.

Click to read the study in Nature Neuroscience

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In-Depth [randomized controlled trial]: In this study, the authors developed a cognitive assessment, or visual retention task, in which subjects were asked to focus on a randomly generated shape for ten seconds. Subjects were subsequently shown two shapes and asked to identify which shape matched the previous one. A high-resolution functional magnetic resonance imaging, fMRI, was used to create three-dimensional brain scans, from which region-specific activity was evaluated.

Thirty-seven adults between the ages of 50 and 69 were enrolled in a three-month trial to evaluate the effect of a dietary flavanol substitute on both cognition and DG function. Trial subjects were segregated into a high-flavanol intake group (900mg cocoa flavanols + high epicatechin) and a low flavanol-intake group (10mg cocoa flavanols + low epicatechin), with or without exercise. Subjects who consumed the high-dose flavanol supplements showed a 26% improvement in task performance at three months. Additionally, this high-dose flavanol group displayed significantly more activity in the DG (p = 0.042). Exercise appeared to have no affect on patient cognitive abilities (p = 0.815).

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