Rationale and design of a randomized controlled trial evaluating the effects of blueberry consumption versus placebo on brain health in older adults

Background

Age-related cognitive decline results in significant clinical and public health costs. Cognitive decline predisposes individuals to dementia and leads to difficulties with activities of daily living and increased hospitalizations. While a few dietary interventions have shown considerable promise at delaying cognitive decline, studies of the effects of long-term blueberry consumption on brain health among older adults have been limited and equivocal.

Objective

To test the hypothesis that a 24-week intervention with blueberry powder versus placebo will improve (i) plasma biomarkers of brain health and (ii) cognitive performance in older adults.

Methods

This randomized, double-blind, placebo-controlled trial will be conducted in older Americans aged 65–99 years old. Sixty-seven participants will be randomly assigned to receive either blueberry powder (20 g/d – equivalent of one (1) cup of fresh blueberries) or a placebo powder (20 g/d) for 24 weeks. Participants will undergo four clinic visits (baseline and 8 weeks, 16 weeks, and 24 weeks after randomization) for cognitive assessments, blood pressure measurements, and blood sample collections. Primary outcomes will be plasma levels of neurofilament light chain (NFL) and phosphorylated tau protein (pTau-181). Secondary outcomes will be plasma levels of glial fibrillary acidic protein (GFAP) and non-esterified fatty acids (NEFA); blood pressure during visits; and cognitive function.

Conclusion

Findings from this trial will answer the question whether a long-term intervention with blueberry powder can improve (i) plasma biomarkers of brain health and (ii) cognitive function in older adults.