Abstract
BACKGROUND AND AIMS: Clinical trials using freeze-dried blueberries on measures of cognition or serum brain biomarkers are sparse or lacking. Our primary aim was to test whether an intervention with freeze-dried blueberries reduces serum phosphorylated tau (p-tau181) and neurofilament light (NFL). Secondary outcomes included serum non-esterified fatty acids, glial fibrillary acidic protein (GFAP), blood pressure, and computer-based cognitive tests.
METHODS: This was a randomized double-blind trial where 57 cognitively healthy subjects were assigned either 20 g/d of freeze-dried blueberry powder or matching placebo for 24 weeks. We collected blood samples for biomarker measurements and administered cognitive tests during each of the four study visits spaced by 8 weeks.
RESULTS: Mean (SD) age at baseline was 73.5 (6.6) years among 28 subjects randomized to blueberry powder and 73.3 (5.2) years among 29 subjects assigned to placebo. There was no statistically significant difference in change over time in serum p-tau181 [i.e., baseline and 24-week adjusted mean (95% CI) were 38.5 (21.3-55.7) and 38.9 (21.7-56.1) pg/mL in the placebo group versus 47.2 (28.9-65.5) and 54.7 (36.3-73.0) pg/mL in the blueberry group] (p for interaction between biomarker and time: 0.10)] or serum NFL [i.e., corresponding values were 26.2 (18.2-34.1) and 25.0 (17.1-33.0) pg/mL in the placebo group and 26.6 (18.2-35.0) and 28.0 (19.5-36.5) pg/mL in the blueberry group, p for interaction 0.58]. In secondary aims, blueberry intervention reduced diastolic blood pressure (p interaction with time 0.015) but there was no effect on systolic blood pressure, cognitive tests, and other biomarkers.
CONCLUSION: A 24-week intervention with freeze-dried blueberries had no effect on serum p-tau181 and serum NFL in older adults.
TRIAL REGISTRATION: NCT05764824, https://clinicaltrials.gov/study/NCT05764824.