The Effect of Anthocyanins on Cognition: A Systematic Review and Meta-analysis of Randomized Clinical Trial Studies in Cognitively Impaired and Healthy Adults.

Abstract

Purpose of the review: Clinical trials suggest that dietary anthocyanins may enhance cognitive function. This systematic literature review and meta-analysis aimed to identify the effect of anthocyanin on cognition and mood in adults.

Recent findings: Using a random-effects model, Hedge's g scores were calculated to estimate the effect size. Across 30 randomized controlled trials, fourteen (n = 733 participants) met the criteria for meta-analysis following PRISMA guidelines (Registration number: CRD42021279470). Qualitative synthesis showed improvements in multiple domains after anthocyanin intake: short-term memory, verbal learning and working memory, executive function, visual-spatial function, psychomotor skills, attention and semantic memory. Four of 15 studies reported significant mood improvements, including anti-fatigue and reduced anxiety and depression scores. However, there were no significant effects for working memory (Hedges's g = -0.183, 95% CI = -0.407 to 0.041, P = 0.110), verbal learning (Hedges's g = 0.054, 95% CI = -0.215 to 0.324, P = 0.69), immediate memory (Hedges's g = 0.196, 95% CI = -0.242 to 0.633, P = 0.38) and delayed memory (Hedges's g = -0.188, 95% CI = -0.629 to -0.252, P = 0.402) according to the meta-analysis. This review suggests potential benefits of anthocyanin intake on cognition and mood. However, in meta-analysis of 14 eligible studies, effects on working, immediate, delayed memory and verbal learning were not significant, likely due to study heterogeneity. Recommendations for future study designs are discussed.