The new research - funded by the US Highbush Blueberry Council - was published in the journal Nutrients. It was the work of researchers associated with institutions in Ohio and Kentucky.
The researchers noted that the risk of developing dementia is a growing issue in the United States as the population ages. Alzheimer’s disease expected to account for 80% of future dementia cases, with as many as 14 million Americans projected to be affected by the year 2050. According to the Alzheimer’s Association, the healthcare costs to the nation will top $1 trillion by that time.
As there is no effective treatment for Alzheimer’s at the moment and no indication that any will developed soon, the onus is on preventive strategies, the authors said. In concord with the rising tide of dementia, the nation continues to experience an increase in obesity, which is one of the risk factors for developing dementia. So the authors said they decided to focus their research on this group.
Backing up preliminary evidence on blueberries
The researchers said preliminary findings had shown that blueberry powder could have some neuroprotective benefits for middle aged individuals suffering from insulin resistance. This is the period in life when the changes that ultimately result in full blown Alzheimers are thought to begin.
To test in a more focused way if blueberry powder could provide neuroprotective benefits the researchers recruited a cohort of 33 (27 of whom completed the study) middle aged overweight men and women who had something called Subjective Cognitive Decline (SCD), which refers to a self-perceived decrement relative to one’s prior cognitive level.
The subjects were ranged from 50 to 65 years old. All them had gained weight in middle life and were aware of cognitive deficits. The participants all had a BMI of 30 or greater.
The study was set up as a double blind, placebo controlled test. The intervention group received freeze dried whole blueberry powder equivalent to a 0.5 cup daily dose of fresh blueberries. An equivalent placebo was provided. Both materials were provided by the US Highbush Blueberry Council, which funded the research. The study lasted for 12 weeks.
The researchers ran the subjects through a battery of cognitive tests and measured insulin levels at baseline and after 12 weeks of supplementation. The tests included a Controlled Oral Word Association Test (often abbreviated as COWA or COWAT), in which the participant supplies as many words as possible that begin with a given letter within a minute.
Another test was the recall intrusion error test, in which a subject recalls a word or object that was not part of a list they were asked to remember. Other tests included memorizing word pairs and a more thorough measurement tool called the California Verbal Learning Test. The researchers also measured blood insulin levels before and after the intervention.
Test scores, insulin level improvements
The authors found that the blueberry powder improved scores on the COWAT test and also reduced recall intrusion errors, but in a statistically significant way. There was no change between the groups on the other tests. The blueberry powder also showed a marked reduction in blood insulin. The blueberry group also reported a reduction in self reported memory problems.
“This study demonstrated that blueberry supplementation has neurocognitive benefit in middle-aged individuals with insulin resistance and elevated risk for future dementia," the authors concluded.
"We observed selective improvement of executive abilities consistent with the notion that ongoing blueberry intake can mitigate deficiencies or deficits, as has been observed numerous times in prior animal and clinical studies. The findings suggest that supplementation has potential for protection against future neurocognitive decline in vulnerable individuals."
2022 Apr 13;14(8):1619. doi: 10.3390/nu14081619.
Blueberry Supplementation in Midlife for Dementia Risk Reduction
Authors: Krikorian R, et al.