BACKGROUND Consumption of polyphenols has been associated with improvements in cognitive function in children (aged 8–10 years old), young adults (18–21 years old) and older adults (65–80 years old). In this study, we investigated the effect of wild blueberry (WBB) consumption on cognitive performance in middle aged adults (45–60 years old) and examined the relationship of cognitive outcomes with metabolic control.

METHODS In this randomized, single‐blind, 2‐arm, cross‐over trial, 29 middle aged men and women were asked to consume a high carbohydrate, moderate fat meal with 1 cup fresh weight equivalent freeze dried WBB drink or control beverage (flavored lemonade). Cognitive tests measuring response interference, executive/working memory, and performance in learning, memory recall and recognition were performed immediately before and every 2 hours after meal consumption for 8 h. Blood samples were collected at defined time points over 8 h after meal intake.

RESULTS Preliminary analysis showed significant effects for treatment (p=0.01) and time (p=0.02) with respect to response inhibition on a task assessing executive function. Response inhibition was significantly higher after WBB consumption compared to control (p<0.05) at the 2 hour time point and a trend for higher response inhibition was observed at the 4 hour time point (p = 0.08). Changes in postprandial insulin were significantly different by treatment (mean ± SE; WBB, 35.0 ± 3.0 uIU/mL, Control, 40.0 ± 3.0 uIU/mL, p=0.02) and time (p<0.0001), whereas glucose and TG were different by time only (p<0.0001 for both). Incremental area under the curve analysis also showed significantly reduced insulin exposure (control, 236.3 ± 32.7 uIU/mL*h vs WBB, 204.8 ± 33.4 uIU/mL*h, p=0.0431) with no significant change in glucose or TG (p>0.05) between WBB and control.