Bilberry, a tasty intervention against age-related cognitive decline

In a recent study published in the Nutritional neuroscience journal, researchers assessed the impact of wild blueberry consumption on the rate of transformation in mild cognitive decline.

According to a 2016 study, 39% of people over the age of 65 had significant cognitive problems, and 68% of them could not live independently. The impact of the aging US population can be mitigated by interventions that have the potential to prevent or reduce the development of cognitive impairment in the aging population. Evidence suggests that the Mediterranean diet, which includes fresh fruits, vegetables, legumes, fish, wine and olive oil, is linked to brain health, with various polyphenols appearing as potential promoters of health.

Study: A six-month intervention with wild blueberries improved processing speed in mild cognitive decline: a randomized, double-blind, placebo-controlled clinical trial. Image Credit: Mircea Costina/Shutterstock

About the study

In the current study, the researchers hypothesized that regular consumption of wild blueberries might increase processing speed, a cognitive skill that underpins all other cognitive abilities.

A total of 296 adults were recruited from the Southeastern United States community aged 65-80. These volunteers were recruited through public events, churches, online publications, media and word of mouth. After an in-person screening visit, 133 of them met the inclusion criteria.

Participants were considered eligible if they had a body mass index (BMI) less than 33, were not taking certain medications, including those with known cognitive side effects or cerebral blood flow restrictions, and had no a history of dementia, Alzheimer’s disease, psychiatric disorders, central nervous system disorders, gastrointestinal or digestive problems, or diabetes. Those eligible also consumed less than five daily servings of fruits and vegetables. The sample was 44% male and 97% self-identified Caucasian.

A randomized, double-blind, placebo-controlled experiment lasting six months was performed. Based on the results of the Montreal Cognitive Assessment (MoCA) during screening, 86 people were identified as having mild cognitive deterioration. The study coordinator randomized these participants to be treated with 35 g of freeze-dried wild blueberry powder or a matching caloric placebo each day. Participants without aging-related cognitive problems were included in a comparison group.

The Wild Blueberry Association of North America provided freeze-dried wild blueberries (Vaccinium angustifolium). The placebo maltodextrin and fructose were combined with artificial and organic flavors and colors. The blind was kept by an administrative staff member outside the laboratory, kept in a sealed envelope. Twice a year the nutrient content was reviewed. A month’s supply of powder packets was provided to intervention participants in insulated lunch bags, each labeled with the date of consumption.

The Stressful Life Events Scale was used to assess stress in an individual’s life. The Physical Activity Scale for Older Adults was used to measure physical activity (PASE). Participants were randomized into intervention or control groups based on their MoCA scores. The MoCA was used as a classification tool. The MoCA was developed to quickly and accurately test for Alzheimer’s disease (AD) and moderate cognitive impairment (MCI). The Wechsler Adult Intelligence Scale, Fourth Edition (WAIS-IV), was used to assess cognitive abilities and intelligence in people aged 16-90. A computerized battery of standardized cognitive tests called CANTAB was used.

Results

The results of the study showed that a post hoc Tukey test found no difference between the blueberry and placebo groups in education or intelligence quotient (IQ). However, by design, it was discovered that the reference group and the intervention groups had different MoCA screening scores. Also, Spatial Working Memory (SWM) Total Errors, Associated Pair Learning (PAL) Mean Trials of Success, Rapid Visual Information Processing (RVP) Total Successes, and Latency Mean RVP were included in a MANOVA with the different groups considered the between-factor subjects.

The results of the multivariate analyzes of the three groups including the IQ scores revealed a between-subjects influence of the group on the mean PVR latency. None of the other dependent variables showed statistically significant group differences. There was also no significance noted in the multivariate model. Over the six-month intervention period, latency (processing speed) for the blueberry group increased but did not differ significantly from the change in latency for the reference group. When the intervention groups were analyzed without the comparison group, the pattern of results was the same, with mean RVP latency now showing a more significant between-subjects effect on the group.

In the frontal group, post hoc analysis showed a tendency for blueberry intervention individuals to outperform placebo participants. Multivariate statistics did not show significance in analyzes that also took into account the additional factor of age group. Nevertheless, similar patterns were found: the major group effect was almost statistically significant in the frontal, left frontal and right frontal clusters.

Maximum amplitude data for 75 to 80 year olds were also processed by a simplified model. Multivariate tests did not yield any significant results. Frontal, central, and median clusters demonstrated a significant group main effect in the between-subjects adjusted model. In all cases, the blueberry group fared better than the placebo group.

Overall, the study results demonstrated that regular consumption of wild blueberries can increase processing speed, especially in people aged 75 to 80. According to the researchers, the present study will allow the development of an animal model that could help identify the mechanisms by which blueberries promote brain function.

Journal reference:

  • Carol L. Cheatham, L. Grant Canipe III, Grace Millsap, Julie M. Stegall, Sheau Ching Chai, Kelly W. Sheppard and Mary Ann Lila (2022), Six-month intervention with wild blueberries improved processing speed in mild cognitive decline: a randomized, double-blind, placebo-controlled clinical trial., Nutritional Neuroscience, DOI: https://www.doi.org/10.1080/1028415X.2022.2117475, https://www.tandfonline.com /doi/full/ 10.1080/1028415X.2022.2117475

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