Dietary blueberry improves cognition among older adults in a randomized, double-blind, placebo-controlled trial

Marshall G. Miller, Derek A. Hamilton, James A. Joseph, Barbara Shukitt-Hale

As populations shift to include a larger proportion of older adults, the necessity of research targeting older populations is becoming increasingly apparent. Dietary interventions with blueberry have been associated with positive outcomes in cell and rodent models of aging. We hypothesized that dietary blueberry would improve mobility and cognition among older adults. In this study, 13 men and 24 women, between the ages of 60 and 75 years, were recruited into a randomized, double-blind, placebo-controlled trial in which they consumed either freeze-dried blueberry (24 g/day, equivalent to 1 cup of fresh blueberries) or a blueberry placebo for 90 days. Participants completed a battery of balance, gait, and cognitive tests at baseline and again at 45 and 90 days of intervention. Significant supplement group by study visit interactions were observed on tests of executive function. Participants in the blueberry group showed significantly fewer repetition errors in the California Verbal Learning test (p = 0.031, ηp(2) = 0.126) and reduced switch cost on a task-switching test (p = 0.033, ηp(2) = 0.09) across study visits, relative to controls. However, no improvement in gait or balance was observed. These findings show that the addition of easily achievable quantities of blueberry to the diets of older adults can improve some aspects of cognition.