October 26, 2014

expert reaction to cocoa and cognition

Researchers have published their findings in the journal Nature Neuroscience that diets high in flavanols, such as those found in cocoa, have beneficial effects in terms of neurology. In a small trial, they found that participants on a high flavanol diet performed better in cognitive tests, and were observed to have improved hippocampi as measured by fMRI.

Dr Ashok Jansari, Cognitive Neuropsychologist, Department of Psychology, Goldsmiths College (University of London), said:

“This exciting study isolates a part of the ‘memory centre’ of the brain known as the hippocampus and a particular section within it called the dentate gyrus. This area is important because while there is a general weakening of hippocampal functioning with age, the dentate gyrus is seen to be particularly involved in this HEALTHY age-related decline. Crucially, this area is different to another area within the hippocampus, the ‘entorhinal cortex’ which seems to be affected in Alzheimer’s Disease and therefore the functional integrity of the dentate gyrus is of special interest given that globally, there is a growing ageing population and the majority of these are neurologically healthy and are not affected by Alzheimer’s.

“By refining very complex neuroimaging techniques that allow changes in biological activity to be measured, the authors were able to examine how functioning of the gyrus is affected by certain chemicals found in cocoa called flavanols. The authors found that a diet high in these flavanols significantly improved speed with which older participants were able to recognise abstract visual patterns. They conclude that their novel findings could prove to be a very useful non-pharmacological aid to battle normal age-related decline in certain aspects of memory.

“There are a few limitations of the study largely to do with the size of the sample. However, given the complexity of the design of the study and its longitudinal nature requiring follow-up over three months, the findings simply suggest that larger scale and longer-term follow-ups are required. The fact that the task used was recognition of novel visual patterns and that the improvement was in faster performance is vitally important since although being able to remember what you did twenty or thirty years ago is useful, from an evolutionary perspective a crucial and possibly defining aspect of human memory is the ability to take in new information and respond to it quickly when we next encounter this once-alien object.

“Given a globally ageing population, by isolating a particular area of the brain that is weakening in functioning as we grow older, and demonstrating that a non-pharmacological intervention can improve learning of new information, the authors have made a significant contribution to helping us improve our cognitive health.”

Dr Clare Walton, Research Manager, Alzheimer’s Society, said:

“This well-designed but small study suggests the antioxidants found in cocoa can improve cognitive performance by improving blood flow to a certain region of the brain. This brain region is known to be affected in ageing, but as yet we don’t know whether these brain changes are involved in dementia.

“With the winter nights setting in, many of us will be settling down with a nice hot cup of cocoa at the end of our day. However, the jury is still out as to whether partaking in things high in antioxidants can improve your memory or reduce your risk of dementia.”

Dr Liz Coulthard, Consultant Senior Lecturer in Dementia Neurology, University of Bristol, said:

“This study hints at a reversal of age-related memory loss through dietary modification which is an appealing prospect for an ageing population, particularly when the dietary supplement is cocoa-based.

“Participants taking high levels of cocoa flavanols were faster to recognise objects they had previously seen than those taking low levels of flavanols. Using state-of-the-art MRI scanning, the authors were able to demonstrate that this improved recognition correlated with increased blood flow to a small area of the hippocampus, the dentate gyrus, thought to be particularly susceptible to age-related decline.

“Although promising, the results should be interpreted with caution for several reasons including: group sizes were small (only 37 participants overall); there were small differences in caffeine and theobromine levels in the high and low flavanol cocoa sachets making it possible that substances other than flavanols mediated the effects; only reaction times, and not accuracy of performance, were actually improved and being faster without being more accurate is not always an advantage and finally; it is not clear that memory is directly improved, perhaps instead participants are just paying better attention to the task.

“It would be very exciting if such a cognitive benefit of flavanols were shown in a larger study that probed several aspects of cognition.”

Dr Simon Ridley, Head of Research at Alzheimer’s Research UK, said:

“This very small trial highlights some possible effects of flavanols found in cocoa beans over a short time period, but we’d need to see much longer, large-scale studies to fully understand whether a diet high in these flavanols could boost cognition in old age. We also don’t know how meaningful the improvements measured in the tests used here would be for people in their daily lives. This study didn’t look at dementia, and we can’t know from this research whether a diet high in cocoa would have any effect in either preventing or delaying the onset of the condition. The supplement used in this study was specially formulated from cocoa beans, so people shouldn’t take this as a sign to stock up on chocolate bars.

“Continued investment in research is crucial to find ways to protect the brain and prevent the diseases that cause dementia. Although there’s currently no certain way to prevent dementia, research shows that a healthy lifestyle can help reduce the risk of the condition. A healthy diet, regular exercise, not smoking, and keeping blood pressure and weight in check can all help lower the risk of dementia.”

‘Enhancing dentate gyrus function with dietary flavanols improves cognition in older adults’ by Brickman et al. published in Nature Neuroscience on Sunday 26^th  October. 

Declared interests

None declared