The effect of dietary modification on executive function domains in adult individuals with obesity: A systematic review and meta-analysis of randomized controlled trials

Abstract

Background: Recent study suggests that obesity is associated with a broad executive function decline. Several dietary intervention studies may improve executive function domains. This meta-analysis aimed to determine the effect of dietary modification on executive function domains in adult patients with obesity. Methods: This systematic review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Pubmed/Medline, Cochrane Library, Science Direct/SCOPUS, and Google Scholar were systematically searched to obtain articles until April 30th, 2022. The main outcome of interest was the change in executive function domains (inhibition, cognitive flexibility, working memory, verbal fluency, decision making, and planning). We extracted data on the standardized mean difference (SMD) between the dietary intervention and control groups in change from baseline executive function domains. The meta-analysis with a random effect model was performed using STATA, and the Risk of Bias (RoB 2.0) tool was used to determine the quality of the included studies. Subsequently, to assess the quality of evidence, we used GRADE tools. Results: A total of 10 randomized controlled trials (RCTs) that met the objectives were obtained. This meta-analysis showed that dietary modification improved cognitive flexibility [SMD=0.303 (-0.527 to -0.079), P=0.008, I2= 0%], working memory [SMD=0.601 (0.076 to 1.125), P=0.025, I2=83.6%], and verbal fluency [(SMD=0.223 (0.002 to 0.428), P=0.033, I2=16.3%]. However, most RCTs (six out of 10) had some concerns due to allocation concealment, unclear blinding assessment or participants, and a high dropout rate. Thus, further well-controlled RCTs are needed to confirm these results. Conclusions: Dietary modification might improve executive function domains in adult individuals with overweight/obesity. Registration: This systematic review is registered in the PROSPERO database (CRD42022332572; registered 24 May 2022).