Effect of dietary patterns on cognitive functions of older adults: A systematic review and meta-analysis of randomized controlled trials Dietary Patterns on Cognition of Older Adults

Background: Dietary patterns are associated with cognitive benefits, but inconsistent findings have been reported concerning this association. This study aims to provide a more comprehensive review and higher evidence level by evaluating evidence from randomized controlled trials (RCTs) exploring effects of various dietary patterns on cognitive function outcomes in older adults. Methods: This systematic review and meta-analysis study followed the PRISMA guidelines. Twelves search engines and databases were searched for papers published up until March 2022. Random-effects models were used to calculate effect size (ES).Results: Twenty-two RCTs met our inclusion criteria. A wide range of cognitive measures were used across the included studies. To reduce heterogeneity and to ensure a sufficient number of studies for meaningful interpretation, we utilized global cognition as the outcome measure. Only nine studies used global cognition measures, including the Mini-Mental State Examination (MMSE), Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), Cognitive Abilities Screening Instrument (CASI), or neuropsychological test battery. Additionally, seven dietary patterns were identified in these studies. The results demonstrated that dietary patterns achieved a significant improvement on cognitive function outcomes including the MMSE/CASI (ES = 0.303; 95% CI [0.045, 0.5601), the ADAS-Cog (ES = -0.277; 95% CI [-0.515, -0.0391), and the cognitive battery (ES = 0.132; 95% CI [0.010, 0.2551). Conclusions: Multidisciplinary health-care professionals may use this information as a reference when planning elder care. More large-scale, high-quality studies are required to explore the long-term effects of healthy dietary patterns on global cognition, other cognitive domains, and life quality among older adults.