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

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.