Effects of Anthocyanin-Rich Supplementation on Cognitive Performance and Brain Function of Healthy Middle-aged and Older Adults: A Systematic Review and Meta-analysis

Abstract

Background: The prevalence of age-related cognitive decline has been on the rise as the global population age, putting more people at the risk of neurodegenerative diseases. Anthocyanins, a type of potent antioxidant, have exhibited neuroprotective effects by reducing oxidative stress caused by brain ageing. Therefore, anthocyanin-rich supplementation may potentially become an effective dietary measure to counteract age-related cognitive decline. Aim: This review examined the effects of dietary anthocyanin supplementation on cognitive performance and brain function of adults from middle and old groups. Methods: A comprehensive three-step strategy was adopted to search for published and unpublished English-language randomized controlled trials (RCTs) in seven databases from inception to 17th September 2020. Screening, data selection and risk of bias were conducted by two reviewers independently. Cognitive outcome data were then extracted from the included RCTs for meta-analysis and narrative synthesis. Additional sensitivity and subgroup analysis were conducted to address the heterogeneity among RCTs. Results: Thirteen studies were included in this review with 72.5% of them having low risk of bias. Six neurocognitive domains were evaluated under meta-analysis. Among them, anthocyanin-rich supplementation was found to significantly improve the processing speed of the older participants (Cohen’s d = 0.26; 95% CI [0.08, 0.44]) while comparable effects were observed for other domains. The effects of anthocyanin-rich supplementation on neuroimaging and serum Brain-derived neurotrophic factor (BDNF) concentration are inconclusive due to a lack of studies. Impact: Through meta-analysis, this review systematically assessed the best available quantitative evidence regarding the effects of anthocyanin-rich supplementation on cognition and brain function of people from middle- and old-age groups. The findings highlighted that anthocyanin-rich supplementation may improve cognitive processing speed and emphasized on areas where further research was required.