The effect of grape interventions on cognitive and mental performance in healthy participants and those with mild cognitive impairment: a systematic review of randomized controlled trials

CONTEXT: The prevalence of cognitive and mental health disorders are growing, and existing drug therapies do not treat the underlying cause. Grapes are a flavonoid-rich soft fruit and may therefore be beneficial to cognitive and mental health. OBJECTIVE: To systematically review evidence from randomized controlled trials investigating the acute and chronic effects of grape interventions on measures of cognition and mood in healthy participants and those with mild cognitive impairment. DATA SOURCES: MEDLINE, The Cochrane Library and EMBASE were searched. DATA EXTRACTION AND ANALYSIS: Eight studies met the inclusion criteria: one considered acute interventions, 6 assessed chronic effects, and one assessed acute and chronic effects of grapes. The chronic studies found improvements in some cognitive domains (eg, memory, motor skills, or executive function). Acute studies found no consistent effect on memory but saw improvements in reaction time. CONCLUSIONS: Differences in study design, dosages, and outcome tests hindered between-study comparison. Even so, the results across studies show that grapes can enhance some aspects of cognition, after both acute and chronic interventions. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42020193062.