USHBC-funded research indicates that the consumption of blueberries may help middle-aged individuals counteract cognitive decline.
Specifically, the equivalent of half a cup of fresh blueberries per day, consumed in the form of freeze-dried blueberries powder, was found to help middle-aged individuals counteract cognitive decline when applied early in at-risk individuals.
According to the US Highbush Blueberry Council (USHBC), which supported the funding of the research, this is a major achievement considering that around 6 million older adults in the US are affected by dementia.
As treatments for cognitive decline are limited, preventive approaches and risk reduction through proper nutrition are increasingly important. Since the neurodegenerative changes associated with cognitive decline begin in middle age, this research indicated that blueberries could represent an opportunity for early intervention, targeting modifiable risks such as poor nutrition and related metabolic disorders.
The randomised, double-blind, placebo-controlled trial, 'Blueberry Supplementation in Midlife for Dementia Risk Reduction' ( blueberries supplementation in midlife to reduce dementia risk), examined the impact of blueberries supplementation in producing measurable cognitive benefits in the context of ageing and insulin resistance.
Participants (n = 27) were overweight men and women (BMI > 25) aged 50-65 years with subjective cognitive decline and moderate insulin resistance. Over the course of 12 weeks, participants were randomly assigned to consume freeze-dried blueberry powder or placebo daily.
Participants were asked to consume the powder with their morning or evening meal, mixing it with water. Pre- and post-intervention assessments of cognition and metabolism and exploratory measures of peripheral mitochondrial function were conducted.
The blueberry group recorded better performance on measures of lexical access, such as letter fluency as measured by the controlled word association task, better performance on measures of memory interference, such as fewer intrusive recall errors as measured by the California Verbal Learning Test, and a reduction in memory erosion difficulties in activities of daily living, such as reduced forgetting, as measured by the Everyday Memory Questionnaire.
The blueberries group also experienced a correction of peripheral hyperinsulinaemia, which is associated with brain neurodegeneration, and a significant drop in fasting insulin levels.
Based on these results, the study authors suggested that potential mechanisms for these findings could be associated with anthocyanins and proanthocyanidins, the bioactive flavonoid compounds found in blueberries and responsible for their vibrant blue colour.
Importantly, blueberries may induce metabolic and other benefits that could serve as an early intervention to prevent cognitive decline associated with ageing.
"This is the first study of its kind to examine the supplementation of blueberries in middle-aged individuals at risk of future health problems and dementia in laterlife," said Robert Krikorian, PhD, Department of Psychiatry and Behavioural Neuroscience, University of Cincinnati Academic Health Center and lead investigator of the study.
'This research provides evidence that blueberries supplementation can improve cognitive function and correct high insulin levels in these participants with prediabetes'.
SUPPORT FOR PREVIOUS RESEARCH
The study builds on previous research in this area, which demonstrated improved long-term memory performance with blueberries supplementation in older adults with mild cognitive impairment. The study also supports previous research that has found an association between blueberries consumption and improved metabolic function in at-risk individuals, such as improved insulin sensitivity.
The USHBC stated that further research is needed to examine the integration of blueberries over a longer time period with a more robust sample size. In addition, longitudinal cognitive evaluations would be useful to assess the influence of blueberries on the progression of cognitive decline and to further investigate the mechanisms of neurocognitive benefits.
'Although further studies are needed, our results provide new and exciting data on the potential of blueberries supplementation as a preventive intervention,' Krikorian added.
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