Supplementation with anthocyanins, which are a type of flavonoids mainly found in various berries, is hypothesized to be a promising approach to lower the risk of developing cognitive decline. The aim of this systematic review was to provide a comprehensive overview of dietary intervention trials describing effects of berry anthocyanins on cognitive performance in humans, while also addressing potential underlying mechanisms.
Cognitive performance encompasses multiple mental abilities that can be categorized into various domains, such as attention and psychomotor speed, memory, and executive function [1]. From childhood, cognitive performance quickly improves until young adulthood, after which it gradually starts declining [2]. Therefore, it is becoming increasingly relevant to focus on improving and/or maintaining cognitive performance to delay and prevent cognitive decline, and ultimately the onset of dementia [4][3]. This could be achieved by targeting potential mechanisms that drive cognitive performance [5,6][4][5].
An impaired vascular function is a common pathophysiological characteristic of multiple age-related conditions [7,8][6][7]. Vascular function can be assessed by determining endothelial function with methods such as brachial artery flow-mediated vasodilation (FMD) or the reactive hyperemia index (RHI) [9][8]. Previous research has already shown that vascular health declines with age leading to an increased risk of cognitive impairment, which may partly be explained by co-existing cardiometabolic risk factors, such as high blood pressure (BP) or a disturbed lipid profile such as altered low-density lipoprotein cholesterol (LDL-C) or high-density lipoprotein cholesterol (HDL-C) concentrations [11][9]. Therefore, dietary interventions that target vascular function and/or cardiometabolic risk markers may improve cognitive performance [14,15,16][10][11][12].
Therefore, increasing dietary intake of anthocyanins through supplementation could be a useful strategy to lower the risk of developing cognitive decline. A recent systematic review by Kent and colleagues [23][13] reported different intervention studies with beneficial effects of food-derived anthocyanins on cognitive performance. However, a systematic review designed to evaluate the effects of dietary anthocyanin interventions on cognitive performance and underlying mechanisms (i.e., vascular function and cardiometabolic risk markers) in an integrated manner has not been published yet. Therefore, the aim of this systematic literature review was to provide an overview of dietary intervention trials describing effects of berry anthocyanins on cognitive performance, vascular function, and cardiometabolic risk markers in humans.