(CNN) -- As the number of Americans living with Alzheimer's disease continues to rise, researchers are investigating various ways that people can prevent memory decline through nutrients in foods we might eat often anyway.
So far, nothing has been proven to work for sure, but there's no harm in eating healthy foods.
The latest target of interest is berries. A study of more than 16,000 women over age 70 suggests there is a connection between berries and memory problems. Specifically, women who ate the most berries per week were likely to have up to a 2.5-year advantage in terms of when they showed signs of memory decline.
There's no reason think that results would be different in men, said the study's lead author, Elizabeth Devore, researcher at the Channing Laboratory at Brigham and Women's Hospital in Boston.
But note that this study, published in Annals of Neurology, received funding from the California Strawberry Commission - a potential conflict of interest. The data analysis, writing and results were done completely independently of this sponsor, however, Devore said, and did not have anything to do with the concept of the study.
Participants were asked about food consumption every four years since 1980, and their memory was tested every two years between 1995 and 2001. Researchers found that the women who ate at least 1/2 cup of blueberries per week, or two 1/2 cups of strawberries, showed the greatest benefits.
"I'd recommend that both men and women eat more berries," Devore said.
Here's how berries might help: mitochrondria are energy generators of brain cells, and have been thought to also produce substances toxic to the brain that lead to Alzheimer's disease. These toxic compounds are called "free radicals," which damage brain cells and impair cellular processing. Berries are rich in flavonoids, which can act as antioxidants, interacting with free radicals before they cause damage.
But read the results of the new study with caution, says Dr. William Hu, assistant professor of neurology at Emory University School of Medicine. The study authors did not control the diets of the participants - the information about berry intake is based on their own recollections.
And it's hard to directly translate the effect of berries on cognitive decline when other lifestyle factors may also contribute to prevention. The berries themselves may have only a modest role to play.
Hu also noted that the study authors did not control for the presence of a particular genetic variant, called ApoE4, that predisposes people to develop Alzheimer's disease. Devore said her team didn't consider it because genetic variants wouldn't be associated with berry intake. And a separate study looking at a group of women in the Nurses' Health Study found the frequency of the Alzheimer's associated gene similar to what's been reported in older Caucasian women in other large studies.
Exercising, doing puzzles and other mind-stimulating activities, having a social support network and eating a healthy, balanced diet have all been suggested in previous research to contribute to preventing cognitive aging.
"I don't think that any one of these factors is the silver bullet," Hu said.
Still, it doesn't mean you should stop eating berries, either. Hu and his wife eat strawberries every night.
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