The study was the work of Dr Robert Krikorian, Associate Professor of Clinical Psychiatry at the University of Cincinnati Academic Health Center in Cincinnati, Ohio and colleagues, and a report about it appears in the 4 January ASAP issue of the American Chemical Society's bi-weekly Journal of Agricultural and Food Chemistry.
The authors wrote there is an urgent need to develop preventive approaches to dementia which is on the rise as our population ages and there is no effective therapy for it.
Blueberries contain polyphenols, comprising mostly anthocyanins, which are known to have antioxidant and anti-inflammatory effects, combating oxidative stress, which contributes to some neurodegenerative and cardiovascular diseases.
A paper in a February 2008 issue of the Journal of Agricultural and Food Chemistry, that presented the findings of the 2007 International Berry Health Benefits Symposium, suggested that these compounds have beneficial effects on cancer, aging, neurological diseases, inflammation, diabetes and bacterial infections.
The authors also wrote that animal studies have found they contribute to increased neuron-to-neuron communication, improved use of glucose in the brain, and are involved in memory function.
It would be reasonable to expect, therefore, that such compounds might delay neurodegeneration in humans, hence the motive for this work.
For the study, Krikorian and colleagues recruited 9 people in their 70s showing early signs of memory changes, got them to complete memory and cognition tests, then asked them them to drink two to two and a half cups of commercially available blueberry juice a day.
12 weeks later, the volunteers underwent the same memory and cognition tests. When they compared the before and after results, the researchers found the volunteers who had drunk blueberry juice had improved paired associate learning (p = 0.009) and word list (p = 0.04) recall. The results also showed a trend toward reduced depressive symptoms (p = 0.08) and lower glucose levels (p = 0.10), said the researchers.
These results were then compared with the results of another trial of the same design involving a demographically matched group of people in their 70s who also had early signs of memory changes, but this time they were given a placebo that they thought was blueberry juice.
The researchers said that the improved performance of the blueberry group over the placebo group on the paired associated memory test was similar to the difference in the before and after results observed in the blueberry group in the earlier trial.
They concluded that:
"The findings of this preliminary study suggest that moderate-term blueberry supplementation can confer neurocognitive benefit and establish a basis for more comprehensive human trials to study preventive potential and neuronal mechanisms."
"These preliminary memory findings are encouraging and suggest that consistent supplementation with blueberries may offer an approach to forestall or mitigate neurodegeneration," they wrote.