Effect of Grape and its Derivatives on Cognitive Function: A Systematic Review of Clinical Trials

Background: According to the world health organization (WHO), in 2019, around 50 million people suffer from dementia, worldwide; and approximately 60% live in low- and middle-income countries. Dementia has physical, psychological, social, and economic effects on dementia sufferers, their caregivers, families, and the community. Objectives: This systematic review investigated the effect of short-term and long-term interventions with grapes and their derivatives on different cognitive functions, such as executive function, memory, attention and language in all people. Methods: Pubmed, Scopus, and Proquest were searched until June 12, 2020 for English studies. Clinical trials in which grapes and its derivatives were considered as an intervention and changes of cognition and its components as an outcome, were selected. Two independent individuals assessed the quality of the articles according to Jadad checklist and extracted the information of the articles with inclusion criteria based on a specific table. The differences were resolved with the discussion and opinion of a third person. Results: Nine Studies (211 individuals) were included in the content analysis, of which 3 studies had short-term intervention and 6 studies had long-term intervention with grape juice, freeze-dried grape powder, and a syrup made from grapes (Enoant Syrup). It can be said that the consumption of grapes and its derivatives improved various cognitive components (such as attention, executive function, immediate spatial memory, learning, and driving skill) between groups. Conclusion: In general, long-term intervention with grapes and their derivatives has led to the improvement of some cognitive functions, but its short-term intervention is not very effective and only 2 studies showed improvement in attention speed. However, the included studies were highly heterogeneous and more research is needed using similar cognitive assessment tools.