Does acute supplementation with wild blueberry extract improve cognitive function in older adults? Original paper

In 2 randomized crossover trials in older adults with normal cognitive function, a single dose of wild blueberry extract had little to no effect on cognitive function.

Whether short-term supplementation with wild blueberry extract (WBE) improves cognitive function in older adults.

The outcomes were global cognitive function (based on the combined score from all tests), reaction time, executive function (a composite measure based on scores from multiple tests), and episodic memory (a composite measure based on scores from multiple tests).

A total of 73 older adults (ages 68–75; 60% women, 40% men) who had normal cognitive function (assessed using the Mini-Mental State Examination) and were without apparent health conditions.

Two separate randomized crossover trials were conducted.

In the first trial, 28 participants completed 5 testing sessions in which they took a battery of cognitive tests 4 times on the same day. They completed the test battery at baseline, ingested a single dose of WBE (111 mg, 222 mg, 444 mg, or 888 mg) or a placebo, then completed the same test battery 2, 4, and 6 hours later. Each testing session was separated by a washout period of 1 week.

In the second trial, 45 participants completed 2 testing sessions in which they took a battery of cognitive tests twice on the same day. They completed the test battery at baseline, ingested a single dose of either 222 mg of WBE or a placebo, then completed the same test battery again 2 hours later. A washout period of 1 week separated the conditions.

The goal of these studies was to investigate whether WBE could offset the commonly observed post-lunch decrease in cognitive function. In the first trial, the 3rd and 4th tests occurred 1 hour and 3 hours after consuming a standardized lunch. In the trial study, the 2nd test occurred 1 hour after consuming a standardized lunch.

First trial:

• Executive function was worse on the 3rd test than the 2nd and 4th tests in the placebo condition only, suggesting that WBE might have attenuated the post-lunch decrease.
• WBE improved reaction time on 2 of 3 measures. Reaction time on the 3rd test was faster on 1 measure related to executive function with WBE 888 mg compared to a placebo, WBE 222 mg, and WBE 444 mg. Reaction time on the 3rd test was faster on a measure related to episodic memory with WBE 444 mg compared to a placebo, WBE 111 mg, and WBE 888 mg.

There were no differences between conditions for global cognitive function or episodic memory.

Second trial:

• 1 of 2 measures of reaction time (which was related to executive function) was better with WBE than a placebo.

There were no differences between conditions for global cognitive function, executive function, or episodic memory.

None of the reported beneficial effects were likely to be clinically meaningful, and the researchers did not adjust for multiple comparisons, which increases the risk of false-positive results.

The study was funded by the manufacturer of the WBE, and 2 of the researchers were employed by this company.