Blueberries have antioxidant properties which may protect against cognitive impairment. Ben Pruchnie/ Getty Images

Eating blueberries can offer people some protection against the development of Alzheimer's disease, scientists have shown. Often referred to as a "super fruit" as it has been shown before to reduce the risk of cancer, the blueberry could also prevent cognitive impairment, thanks to its antioxidant properties.

"Our new findings corroborate those of previous animal studies and preliminary human studies, adding further support to the notion that blueberries can have a real benefit in improving memory and cognitive function in some older adults," says lead author Robert Krikorian, who presented the findings at the 251st National Meeting & Exposition of the American Chemical Society (ACS).

In the animal models, the scientists estimated that the beneficial antioxidant effects were due to flavonoids called "anthocyanins", which appeared to improve the animals' cognitive skills. Krikorian and his team, from the University of Cincinnati wanted to see blueberries' flavonoids had the same effect on humans, and conducted two separate studies for this purpose.

Two studies, two results

The first one examined 47 elderly persons, aged 68 or more. All had mild cognitive impairment, putting them at risk of developing Alzheimer'. During 16 days, half of them was given freeze-dried blueberry powder or placebo powder. To check the impact of the powders, at the end of trial, the researchers tested their memory and language skills, and conducted fMRI scans. In both tests, the participants who had received blueberry powder performed better and displayed greater brain activity.

The results of the second research were not as strong, but still suggested the fruit offered a certain amount of protection to cognitive functions. However memory was not necessarily improved.

This time, it involved a group of 94 volunteers aged 62 to 80 who were not diagnosed with any conditions but still told researchers they were experiencing memory failures on a daily basis. Four groups were constituted and were either give the same blueberry powder as during the first study, a placebo, fish oil (also believed to strengthen memory), or a combination of blueberry powder and fish oil.

"The results were not as robust as with the first study," Krikorian explained. "Cognition was somewhat better for those with powder or fish oil separately, but there was little improvement with memory."

Treating cognitive impairment

This suggests that blueberries show real promises when it comes to treating cognitive impairments, but only when they have already started to develop the disease.

That is why the study participants who had memory problems, but no diagnosed cognitive impairment, didn't get as much benefits from the fruit, according to the researchers.

More research on larger groups and younger participants is needed to see if groups most at risks of developing Alzheimer's disease, can receive a protection early on, before they enter their sixties.

In the UK, in 2015, 850,000 people suffer from the disease, including around 40,000 people under 60.