Megan Brooks
March 15, 2016
Eating blueberries may improve thinking and memory skills in older adults with mild cognitive impairment (MCI), new research suggests.
“There is a very large, basic-science literature ― molecular studies, cellular studies, and animal studies ― that demonstrates cognitive enhancement with blueberries, but there are only just a few human studies to date,” said lead researcher Robert Krikorian, PhD, University of Cincinnati Academic Health Center, in Ohio.
He presented results of two human blueberry studies March 13 at the 251st National Meeting and Exposition of the American Chemical Society (ACS), in San Diego, California.
Memory, Well-being Boost
In one study, 47 adults aged 68 years and older with MCI were randomly allocated to consume a freeze-dried blueberry powder equivalent to a cup of blueberries or a placebo powder once a day for 16 weeks. The researchers carried out pre- and postintervention cognitive tests on all participants and brain imaging in a subset.
“There was improvement in cognitive performance and brain function in those who had the blueberry powder compared with those who took the placebo,” Dr Krikorian reported.
The cognitive tests included a verbal list–learning task, a simple paper-and-pencil line drawing motor task, a visual-spatial memory task that involved nonverbal information, and a semantic access task. In the blueberry group, there was a significant 72% improvement in semantic access and a 13% improvement in visual-spatial memory, Dr Krikorian told Medscape Medical News. “And we had marginal effects for the other tests ― that is, trends that were close to significant but didn’t reach significance.
“In addition, we found that the blueberry-supplemented subjects showed increased activation in certain regions of the left hemisphere of the brain, and that did not occur with placebo-powder subjects,” he said.
The other study included 94 adults aged 62 to 80 years who had complaints concerning subjective memory. They were randomly allocated to receive the blueberry powder, fish oil, fish oil plus the blueberry powder, or placebo for 24 weeks.
“This study was of similar design but involved a larger population of older adults with normal cognitive function, and the supplementation period was 24 weeks as opposed to 16. The findings weren’t as robust in this study,” Dr Krikorian said, perhaps because these patients had less severe cognitive problems when they entered the study.
“The other interesting result was that the blueberry-supplemented participants felt they were performing better in their everyday lives. They had a better sense of well-being and were making fewer memory mistakes and were less inefficient than they had been relative to those that received the placebo powder,” he noted.
The beneficial effects of blueberries could be due to the presence of anthocyanins, flavonoids shown to improve cognition in animals, Dr Krikorian said.
“It’s important to do this work and for other programs as well to replicate what we are finding,” he noted. “And we need to know much more about the mechanisms of action and the proper dose and intervention period. There are a host of questions that have to be answered with human research.”
Interpret With Caution
These findings are “intriguing but should be interpreted with caution,” Keith N. Fargo, PhD, director of scientific programs and outreach, Alzheimer’s Association, noted in an interview with Medscape Medical News.
“I think the thing for people to remember here is that it is a small study, so there may be something here, [or] there may not be something here. Other people have looked at blueberries and found some protective effect, so it’s not outside the realm of possibilities, and if it’s true, it could be exciting,” Dr Fargo said.
“As a population, we are aging, and it’s going to be important for all of us to try to eat as healthy as we can,” he added. “It’s probably not about a single dietary change. It’s probably about making sure you are physically active and keeping your body weight in check and making sure you are eating a reasonable diet. Those things are going to be helpful for your cardiovascular health, and things that are helpful for your cardiovascular health are also helpful for your cognitive function as you age,” he added.
Funding for the studies was provided by the US Highbush Blueberry Council, the National Institute on Aging, and Wild Blueberries of North America. Dr Krikorian has disclosed no relevant financial relationships.