Polyphenol-Rich Cocoa Extracts Protect Against Alzheimer's Disease

A recent paper suggested that flavonol-rich cocoa extracts interfere with the processes that lead to the development of Alzheimer's disease.

Alzheimer's disease (AD) is characterized by pathological aggregates of amyloid peptide-beta (Abeta) and tau protein. Currently available therapies ease AD symptoms but do not slow progression of the disease.

Previous studies have reported that polyphenol-rich diets reduce the risk for developing AD. In the present study, investigators at the Icahn School of Medicine at Mount Sinai (New York, NY, USA) evaluated the AD disease-modifying effects of cocoa, a rich source of flavanols, which are a class of polyphenols.

The investigators tested the effects of three different cocoa extracts (Natural, Dutched, and Lavado), on Abeta42 and Abeta40 oligomerization, using the photo-induced cross-linking of unmodified proteins technique. To assess the effects of cocoa extracts on synaptic function, they measured long term potentiation in mouse brain hippocampal slices exposed to oligomeric Abeta.

Results published in the June 23, 2014, online edition of the Journal of Alzheimer’s Disease revealed that cocoa extracts were effective in preventing the oligomerization of Abeta, with Lavado extract being most effective. Lavado extract, but not Dutched extract, was effective in restoring the long term potentiation response reduced by oligomeric Abeta. The Dutch process lowers acidity, increases solubility, enhances color, and smoothes flavor. Compared to other processes, Dutch process chocolate contains lower amounts of flavonols.

“Our data suggest that Lavado cocoa extract prevents the abnormal formation of Abeta into clumped oligomeric structures, to prevent synaptic insult and eventually cognitive decline,” said senior author Dr. Giulio Maria Pasinetti, professor of neurology at the Icahn School of Medicine at Mount Sinai. “Given that cognitive decline in Alzheimer’s disease is thought to start decades before symptoms appear, we believe our results have broad implications for the prevention of Alzheimer’s disease and dementia.”

“There have been some inconsistencies in medical literature regarding the potential benefit of cocoa polyphenols on cognitive function,” said Dr. Pasinetti. “Our finding of protection against synaptic deficits by Lavado cocoa extract, but not Dutched cocoa extract, strongly suggests that polyphenols are the active component that rescue synaptic transmission, since much of the polyphenol content is lost by the high alkalinity in the Dutching process.”

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Icahn School of Medicine at Mount Sinai