Researchers from the Department of Food and Nutrition in Chung-Ang University, Korea, showed rats subjected to stress but given blueberry drinks for eight weeks performed better in cognitive function tests.
“Stress-induced cognitive impairment is related to the suppression of hippocampal neurogenesis that results from an increase of oxidative stress,” wrote the researchers.
“Psychological stress can induce dysfunctions in the nervous system, including cognitive impairment, anxiety, and insomnia. Recent studies have shown that both intense acute and chronic stress can have detrimental neurocognitive effects and repeated stress induces neurochemical and neuroanatomical changes in the brain, mainly in the HPA axis.”
The rats were divided into four groups. The control group had water and was not subjected to stress. The second received blueberry supplementation and also wasn’t subjected to stress.
The third group was subjected to stress and drank water. The fourth group was also subjected to stress but was given blueberry.
After eight weeks, maze testing began. Researchers measured the time the rats took to finish a T-maze test and the number of errors they made when they entered the blind alley.
They found the rats subjected to stress, yet supplemented with blueberry, recorded to similar times to stress-free rats.
Meanwhile, those subjected to stress but given only water took almost double the time.
Significantly, on the second day of testing, the rats subjected to stress and given the blueberry drink recorded the quickest times of all groups.
The induced stress also affected the rats’ feeding habits. Both groups of rats exposed to stress lost weight.
“The blueberry drink did not restore the feed intake, nor did it ameliorate the body weight loss caused by the chronic stress,” added the researchers.
The study suggested that the stressed rats fed with blueberry drinks’ improved performance in the T-maze tests may be due the antioxidant and neuroprotective effects of the blueberry’s high concentrations of polyphenols and flavonoids.
“Our findings suggest that blueberry supplementation may protect against the cognitive impairment induced by chronic psychological stress,” said the researchers.
“Based on these findings, blueberry appears to have potential benefits in terms of prevention of a cognitive decline during stress, and these effects may extend to the cognitive decline associated with other neuropathic diseases.”
Our colleagues in the US recently reported on blueberry's blood sugar management benefits.
Source: Nutrition Research and Practice
“Protective effects of blueberry drink on cognitive impairment induced by chronic mild stress in adult rats”
Authors: Qian Guo, Young-Nam Kim and Bog-Hieu Lee