Blueberries for brainpower: A systematic review and meta-analysis with Bayesian post hoc analysis of RCTS exploring cognitive function in the elderly with prior cognitive decline.

Abstract

Blueberries are anthocyanin-rich fruits widely consumed by the general population, with well-established health benefits on the endocrine and cardiovascular systems attributed to their potent anti-inflammatory properties. However, the potential impact of blueberry consumption on cognitive function in elderly individuals with prior cognitive decline, such as Alzheimer's disease and dementia, remains insufficiently explored in the literature. Therefore, we aimed to evaluate the potential effects of chronic blueberry consumption on cognitive performance in this population through various memory assessment tools. We searched PubMed, Embase, and Cochrane for randomized controlled trials (RCTs) evaluating the effect of chronic blueberry consumption on cognitive function. We pooled standard mean differences (SMD) and 95% confidence interval (CI) using a random-effects model. We identified nine eligible RCTs involving 513 patients. In elderly individuals with mild cognitive impairment (MCI) and subjective cognitive decline, blueberry intake showed a statistically significant improvement in episodic memory. (SMD = 0.34; 95% CI 0.11 to 0.57; p < 0.05). The subgroup analysis revealed that diagnostic objetivity was not a statistically significant effect modifier. Blueberry intake was also associated with improved language memory in MCI patients (SMD = 0.30; 95% CI 0.01 to 0.60; p < 0.05). No improvements were seen in processing speed (SMD = - 0.33; 95% CI - 0.85 to 0.19, p > 0.05), recognition memory (SMD = 0.14; 95% CI - 0.17 to 0.46, p > 0.05), visuospatial learning (SMD = 0.32; 95% CI - 0.16 to 0.79, p > 0.05) and working memory (SMD = 0.09; 95% CI - 0.21 to 0.39, p > 0.05). Chronic blueberry intake may improve episodic memory in the elderly with MCI and subjective cognitive decline, and also language in the elderly with MCI. These findings should be confirmed in further multicenter trials to confirm generalizability and long-term impact.