Enhanced neural activation with blueberry supplementation in mild cognitive impairment

Abstract

Objectives: Preclinical studies have shown that blueberry supplementation can improve cognitive performance and neural function in aged animals and have identified associations between anthocyanins and such benefits. Preliminary human trials also suggest cognitive improvement in older adults, although direct evidence of enhancement of brain function has not been demonstrated. In this study, we investigated the effect of blueberry supplementation on regional brain activation in older adults at risk for dementia.

Methods: In a randomized, double-blind, placebo-controlled trial we performed pre- and post-intervention functional magnetic resonance imaging during a working memory (WM) task to assess the effect of blueberry supplementation on blood oxygen level-dependent (BOLD) signal in older adults with mild cognitive impairment, a risk condition for dementia.

Results: Following daily supplementation for 16 weeks, blueberry-treated participants exhibited increased BOLD activation in the left pre-central gyrus, left middle frontal gyrus, and left inferior parietal lobe during WM load conditions (corrected P < 0.01). There was no clear indication of WM enhancement associated with blueberry supplementation. Diet records indicated no between-group difference in anthocyanin consumption external to the intervention.

Discussion: These data demonstrate, for the first time, enhanced neural response during WM challenge in blueberry-treated older adults with cognitive decline and are consistent with prior trials showing neurocognitive benefit with blueberry supplementation in this at-risk population.

Keywords: Aging; Blueberries; Brain activation; Dementia; MCI; fMRI.

Figure 1.

Increased blood oxygen level-dependent (BOLD) signal during memory loading conditions in blueberry-treated group in the left pre-central gyrus, left middle frontal gyrus, and left inferior parietal lobe after intervention relative to pre-intervention baseline (corrected p < 0.01).

Figure 2.

Evaluation of Group-by-Visit interaction; 2nd order, 3-factor (Group, Visit, and Participant), identified two regions of significantly higher blood oxygen level-dependent (BOLD) signal after blueberry supplementation (corrected p < 0.01), left inferior parietal lobule and left pre-central gyrus.

Figure 3.

Mean daily consumption (mg/day) of anthocyanin compounds in the background diet for the blueberry- and placebo- treated groups calculated from diet diaries obtained during the week before enrollment (baseline), week 8 of the intervention (interim), and during the final week of the intervention. Separate repeated measures analyses for each anthocyanin compound indicated main effects for time for cyanidin (p = 0.01), malvidin (p = 0.05), peonidin (p = 0.05), and a trend for time for petunidin (p = 0.08). However, there was no group by time interaction that would indicate a betweem-group difference in such consumption outside the intervention.