Cognitive response to fish oil, blueberry, and combined supplementation in older adults with subjective cognitive impairment

Abstract

Given evidence that eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and anthocyanin-rich blueberries provide neurocognitive benefit, we investigated long-term supplementation in older adults with cognitive complaints. In a 24-week randomized, double-blind, placebo-controlled trial, elderly men and women received daily fish oil (FO) or blueberry (BB) or both. Diet records confirmed that participants reduced background consumption of EPA, DHA, and anthocyanins as prescribed. Erythrocyte EPA + DHA composition increased in the FO groups (p = 0.0001). Total urinary anthocyanins did not differ between the groups after supplementation but glycoside and native (food) forms increased only in the BB-supplemented groups. The FO (p = 0.03) and BB (p = 0.05) groups reported fewer cognitive symptoms, and the BB group showed improved memory discrimination (p = 0.04), indicating that supplementation improved cognition. Cognitive benefit in the BB group was associated with the presence of urinary anthocyanins reflecting recent BB intake but not with anthocyanin metabolites. However, combined FO + BB treatment was not associated with cognitive enhancement as expected.

Trial registration: ClinicalTrials.gov NCT01746303.

Keywords: Aging; Anthocyanins; Blueberries; Dementia; Memory; Omega-3 fatty acids.

Conflict of interest statement

Disclosure Statement

None of the other authors has actual or potential conflict of interest, including financial, personal or other relationships with individuals or organizations that could inappropriately influence or be perceived as influencing their work.

Copyright © 2017 Elsevier Inc. All rights reserved.

Figures

Figure 1

Mean daily intake (g/d) of EPA+DHA in the background diet by group determined from three-day diet records obtained during the week before enrollment (Baseline), the week before the interim visit (week 12), and during the final week of the intervention (week 24). Repeated measures ANCOVA indicated effect for time, F = 11.53, p < 0.000.

Figure 2

Anthocyanin consumption (mean daily intake, mg) in the background diet by group determined from three-day diet records obtained during the week before enrollment (B), before the interim visit (week 12), and during the final week of the intervention (week 24). Separate repeated measures analyses indicated reduced external consumption of cyanidins, p = 0.03, pelargonidin, p = 0.04, malvidin, p = 0.00, peonidin, p = 0.00, and petunidin, p < 0.0001. A significant group by time interaction was evident for pelargonidin only, p = 0.04.

Figure 3

Cognitive symptoms in everyday activities as measured by the Dysexecutive Questionnaire (DEX) were reduced after 24 weeks’ treatment for participants receiving fish oil (FO), F(1,32) = 4.94, p = 0.03 and those receiving blueberry powder (BB), F(1,35) = 3.99, p = 0.05. Lower scores indicate less symptom disturbance. Error bars = SEM.

Figure 4

Recognition memory discrimination performance for the Hopkins Verbal Learning Test (HVLT). The BB-treated group exhibited greater accuracy indicating improved discrimination of target from non-target items, F(1,35) = 4.24, p = 0.04. Error bars = SEM.